The collection of books included a stock of approximately a million volumes previously housed in the NDL's temporary main library in Akasaka, which consisted of those transferred from the libraries of the houses of Representatives and Peers along with those acquired after the war, as well as approximately a million volumes previously housed in the Ueno Branch Library, most of which had been acquired prior to the war.
収蔵された図書は、貴衆両院図書館からの引継書と戦後の収集分からなる赤坂の国会図書館仮本館蔵書が約100万冊、帝国図書館による戦前収集分を基礎とする上野図書館の蔵書が約100万冊。