A library apparatus in which a plurality of cartridges can be charged or discharged at the same time, with a simple and compact configuration of a magazine load/unload portion, is disclosed. A plurality of cartridges each containing a storage medium are accommodated in a magazine. The cartridges are moved to a drive unit by a built-in accessor thereby to process the storage media. A charge/discharge mechanism for setting the magazine in the apparatus is configured of an outer door arranged on the front of a frame unit for establishing communication between the exterior and the interior of the apparatus and adapted to be opened/closed manually from outside, an inner door arranged on the back of the frame unit and opened/closed mechanically by the insert/discharge operation of the magazine, and a lock mechanism for the inner and outer doors arranged under the frame unit.