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Mission and Roles


The National Diet Library (NDL), founded in 1948, is the library belongs to the Diet. It is established by the National Diet Library Law, based on Article 130 of the Diet Law, "The National Diet Library shall be established in the Diet by a separate law, in order to assist Diet Members in their study and research."

The law declares the mission of the library's establishment in its preamble: The National Diet Library is hereby established as a result of the firm conviction that truth makes us free and with the object of contributing to international peace and the democratization of Japan as promised in our Constitution. It sets the library's objective in Article 2: The National Diet Library shall collect books and other library materials for the purpose of assisting the members of the National Diet in the performance of their duties and also for the roles of providing certain library services as hereinafter specified for the executive and judicial agencies of the national government and for the people of Japan.

The Firm Conviction that Truth Makes Us Free

At the Hall of the Main Building, this phrase is engraved both in Japanese and Greek. The Japanese inscription is in the hand writing of Tokujiro Kanamori (1886-1959), who was the first Librarian of the NDL and also served as the minister of state in charge of Constitutional Law at the time the Constitution was enacted.

Under the firm conviction that truth makes us free, the NDL is positioned to serve the information needs of both the National Diet and the Japanese public.

For more detailed information, please refer to the Japanese page.

Picture of the inscription above Counter of Tokyo Main Library Picture of the inscription in Greek above Counter of Tokyo Main Library

Services & Roles

Services for the Diet

One mission of the National Diet Library (NDL) is to assist the activities of the Diet by supplying appropriate analysis and information. The NDL therefore provides legislative research and information services at the request of the Diet members, in addition to offering them reading, lending and copying services of library materials. All departments of the NDL work together to ensure satisfactory Services for the Diet.
The Research and Legislative Reference Bureau, a legislative support organ of the Diet, carries out wide-ranging research on national issues including the political, economic and social systems of Japan and other countries, using large amounts of materials and internal and external databases. The number of answers provided by the Bureau in response to requests from Diet members and Diet staff is approximately 40,000 a year.
The research papers, other publications, the “Full-text Database of the Minutes of the Diet (jointly constructed with both Houses),” “Database System for the Minutes of the Imperial Diet” and the “Index Database to Japanese Laws, Regulations and Bills” which the Research and Legislative Reference Bureau provides and develops for the Diet deliberations, are available not only to the Diet members but also to the general public on the NDL website (in Japanese).

  • Services for the Diet
  • Legislative information
    Publications by the Research and Legislative Reference Bureau created as reference materials for the Diet deliberations (photo on the right) are available. (Publications are only in Japanese.)

Services for the executive and judicial branches

The NDL has branch libraries within the government ministries and agencies and the Supreme Court, thus extending its services such as lending, copying and reference services to the executive and judicial branches of the government. The NDL, the central library, and its branch libraries work in concert through a communications network, and cooperate on library activities such as exchange of official publications of government ministries and agencies, interlibrary loan, and staff training for librarians in the branch libraries. The NDL also operates the “Total System of the NDL and Branch Libraries” and provides several services such as a distributed union catalog database enabling a search of each library's catalog.
Through this Branch Libraries System, publications of the executive and judicial branches are deposited to the NDL.

Public services

The NDL provides services at the Tokyo Main Library, Kansai-kan and International Library of Children's Literature (ILCL), as well as via other libraries and the Internet (online service).

Services available by visiting the library

Anyone 18 years old or over of any nationality is eligible to visit the NDL and use the services. *
Most of the materials of the NDL are stored in closed stacks and user registration is necessary to use them. For information on user registration and how to apply, please see User Registration. Without user registration, materials on open shelves in the special materials rooms, digital images of the NDL collections, and subscribed e-journals are available. Library materials can be requested for paid copying services within the scope of the Japanese Copyright Law. Individuals are not allowed to take materials out on loan from the library.

The ILCL provides services to users under 18 years old as well. If you are under 18 years old and wish to use the materials of the Tokyo Main Library and the Kansai-kan, please consult us beforehand. For details, see FAQ.

Services available via other libraries

The NDL provides reader service by delivering materials to public and university libraries *. You can also request copying and reference services through the libraries.

indicates those libraries which are affiliated with the NDL interlibrary loan system. As there may be some materials which cannot be loaned out, please ask the libraries beforehand.
The ILCL provides lending services of selected sets of books which consist of 40-60 children's books assembled by subject (“Book Sets Lending Service to School Libraries”) and copying and reference services to school libraries.

The NDL provides Digitized Contents Transmission Service for Libraries in Japan, in which digitized versions of the NDL holdings that are out-of-print or otherwise difficult to obtain are available in domestic libraries and institutes that have become partners of the NDL.

Digital Contents and Catalogues

Databases and digital images of materials on the NDL website are available to anyone at any time.

  • Digital Contents and Catalogues
  • National Diet Library Digital Collections
    The NDL has digitized more than two million items of books, periodicals, rare and old materials, doctoral dissertations and others. Among them, copyright-free items are available on the Internet. Digitized versions of out-of-print materials or difficult-to-obtain items of some copyrighted materials are also available in domestic libraries that applied for and received authorization from the NDL.
    Current situation of digitized contents as of March 2016
    (unit: item)
    Material type Available Online Available via Digitized Contents Transmission Service Available only at the NDL Total
    Total * 500,000 1,415,000 600,000 2,515,000
    Rare books and Old Materials 70,000 20,000 - 90,000
    Books 350,000 500,000 50,000 900,000
    Periodicals 9,000 780,000 450,000 1,235,000
    * Including official gazettes, doctoral dissertations, and other materials.
  • NDL Search
    Collections and digital materials owned by libraries (including the NDL), museums, archives, academic research institutes, etc. in and out of Japan can be searched at once and in various ways. Search results contain links to digitized materials, and introductions on how to use or obtain the material.
  • National Diet Library Great East Japan Earthquake Archive (HINAGIKU)
    The NDL Great East Japan Earthquake Archive is a portal site which enables integrated search of related books, sound sources, videos, photos, websites and others operated in collaboration with organizations collecting records of the earthquake disaster. Its aim is to hand down all records and lessons to future generations and to utilize them for the restoration and reconstruction of the affected areas as well as for disaster-prevention and damage control measures.
    Other than the services above, the NDL creates catalogs of the holdings and various bibliographies and indexes, and provides them on the website. As databases to help find information, the RESEARCH NAVI provides tips for searching, background information and recommendation of helpful databases; and the Collaborative Reference Database (in Japanese) provides search for data of reference cases of nationwide libraries and manuals to find resources on specific subjects. The Online Gallery features digital images of NDL's collection with easy-to-understand explanations.
    Remote copying services are available for registered users. In this service, copies of materials which are searchable via The National Diet Library Online Search and Request Service (NDL Online) can be requested via the Internet and received by mail.

Services for people with disabilities

The NDL provides various services and support for users who have difficulty in accessing our materials and information, such as the data transmitting service for persons with print disabilities.

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Acquisition and preservation of library materials

The National Diet Library (NDL), as a national library, acquires, preserves and provides Japanese publications which are the nation's cultural and intellectual assets. The acquisition of library materials is mostly based on the Legal Deposit System, while publications published before the Legal Deposit System came into force, rare and old materials, manuscripts and foreign publications are collected through purchase, donation, etc. The acquisition of Japanese and foreign materials is conducted in accordance with a policy for acquisition of materials.

Legal Deposit System

The National Diet Library Law requires that all publications published in Japan are deposited with the NDL. Through the Legal Deposit System, the NDL broadly collects publications including maps, audio materials, microfilms and CD-ROMs published in Japan. National government agencies, local public bodies and independent administrative corporations deliver a prescribed number of copies of their publications, while private publishers send one.


The NDL purchases extra copies of frequently used materials (books, magazines and newspapers published in Japan). Foreign materials and rare and old materials, which are selected in accordance with a policy for acquisition of materials, are also purchased.

Exchange and donation

Through international exchange with national libraries all over the world, the NDL makes efforts to acquire publications of foreign governments. In addition, many international organizations, including the United Nations, designate the NDL as a depository library and deposit their publications with the NDL. Donations from individuals and groups are also accepted.


The NDL has a duty to conduct appropriate management and to preserve library materials as the cultural heritage of the nation and to assure future access to them.
The NDL is engaged in preventing deterioration by various methods such as media conversion including digitization, restoration of damaged originals as well as disaster prevention, maintenance of stack environment and training programs on preservation, and spreading this information. The NDL has also been testing various methods of preserving digital resources.

Acquisition of Internet information and online publications

The NDL exhaustively collects Internet information put out by public institutions and private online publications (e-books and e-magazines). (Charge-free private online publications without Digital Rights Management (DRM) are under this obligation at the moment.)
Collected websites are available in WARP, while online publications are available in the National Diet Library Digital Collections. Private online publications are provided only inside the library facilities.

Compilation and provision of catalogs, bibliographies and indexes

The NDL compiles and provides various bibliographies of library materials. Most of the collections are searchable through The National Diet Library Online Search and Request Service (NDL Online) and NDL Search on the website.

Providing National Bibliography

The NDL provides accurate bibliographic information on the newly collected publications published in Japan and Japanese-language materials published in foreign countries, through National Diet Library Bibliographic Records Service (NDL-Bib). Data can be downloaded in the MARC format and in-process bibliographical data is also provided. In addition, they are distributed as JAPAN/MARC (machine-readable version of the national bibliography).

Japanese Periodicals Index

Index for searching articles carried in major Japanese periodicals, approximately 21,000 titles of which 11,000 titles are still published. The NDL provides data which have been accumulated since 1948, on The National Diet Library Online Search and Request Service (NDL Online), etc.

Index Database to Japanese Laws, Regulations and Bills

An online database providing information on the history of Japanese current or abolished laws since 1867. Users can also refer to minutes of the Diet at the stage of deliberation. This is available on the NDL website.

Interlibrary cooperation

Domestic cooperation

The NDL responds to many requests for loan, copy and reference from other domestic libraries. The NDL introduces trends and topics of libraries and library and information science inside and outside Japan through its information bulletin “Current Awareness” and the website “Current Awareness Portal” (mostly in Japanese).

Providing infrastructure for interlibrary cooperation

The NDL carries out research on library and information science and provides various training programs for librarians. It manages the “NDL National Union Catalog Network System” (in Japanese), a union catalog of Japanese books, as well as providing functions to support interlibrary loan between libraries participating in this network system. It also compiles national union catalogs of newspapers, braille and recorded books and children's literature, which are provided in the NDL Search. The NDL also collects data for people with visual disabilities (e.g. audio data in DAISY format, braille data) made by public libraries. The collected data are transmitted to individuals with visual disabilities or libraries via data transmitting services.
In addition, it conducts the “Collaborative Reference Database Project” (in Japanese), which collects and accumulates data of reference cases from the member libraries and provides them on the Internet, as well as allocating the International Standard Identifier for Libraries and Related Organizations (ISIL) to libraries in Japan and maintaining it.

International cooperation

As the sole national library in Japan, the NDL engages in a wide variety of cooperation activities such as library services and mutual visit programs with overseas libraries. It also acts as the Japanese center for the International Standard Serial Number (ISSN) Network and as the Regional Center for Asia for the IFLA Strategic Programme on Preservation and Conservation (IFLA/PAC).

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