The NDL was officially opened to the public on June 5, 1948 in a temporary building using the former Akasaka Detached Palace (Akasaka rikyu), which is now known as the State Guest House (or the Geihinkan).
同年6月5日、旧赤坂離宮（現迎賓館）を仮庁舎として、国立国会図書館は正式に開館した。