The present invention discloses a stack type optical disk changer including a main frame, a cartridge slidably installed on the main frame, a plurality of disk trays slidably stacked in the cartridge, and a cartridge movement preventing means installed in the main frame, for selectively stopping movement of the cartridge. The stack type optical disk changer maintains quality of sound or image of an optical disk, and prevents damages of the optical disk, mis-operations and breakage, by preventing the optical disk from being separated from the tray.