PURPOSE: To control disk transportation by using the top storage shelf of the box of an optical disk library device and managing the conditions of A and B surfaces of an optical disk stored in each storage shelf by an MPU.

CONSTITUTION: A host H.CPU 5 instracts a subordinate MPU 6 of a storage shelf (r) only, which is the return destination of a cartridge 4. Based on this instruction, an optical disk 41 is moved from a driver D, reversed or not reversed and stored in the shelf (r). The facing direction of a surface A or B of the disk 41 is stored in an MEM 61 and a cartridge transport mechanism 3 is controlled by referring to the stored direction of the A or B surfaces. Since only the top section of the storage shelf r0 is used, the number of the cartridges 4 to be stored is increased. Moreover, the cumbersome work loads of the H.CPU 5 is eliminated because the management of the B surfaces is done by the MPU 6.