In the automatic stacks, materials are sorted mechanically. The stacks can hold approximately 1.4 million documents, one of the largest in Japan. The storage capacity of the automatic stacks is about four times that of the fixed stacks.

The stack room contains about 28,000 semi-transparent containers, each of which can hold 50 volumes on average. The container which holds the item requested by the visitor is identified by means of computer.

Materials such as Japanese books that can be controlled using bar-coded labels are stored here.