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Storage environment for National Diet Library

Storing materials under appropriate environmental conditions to protect against inappropriate temperature and humidity, excessive light, dust, insects and air pollution is a very important part of a preservation program. The National Diet Library uses means such as maintaining stacks at about 22 degrees Celsius and about 55% relative humidity, installing automatic lighting devices, etc.

In the main building, stacks are housed in a square cube occupying 17 layers above and below ground at the center of the building and surrounded by offices and reading rooms. The NDL Annex building has offices on its aboveground floors, while all eight floors of the stacks are below ground.


The stacks of the Annex of Tokyo main library are entirely underground, from the first basement to the eighth basement. Stacks underground are not susceptible to extreme fluctuations of temperature outside and are quake-resistant.


Rare book stack(wooden) in stacks


Storage area of microfilm at 18 degree Celcius and 25% relative humidity


Various boxes, various enclosures

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