PURPOSE: To stack decks in stages and to arrange the decks compactly by providing a cassette unloading mechanism which unloads a tape cassette after use to beside a cassette loader device.

CONSTITUTION: After recording or reproduction ends, the tape cassette C is put back into the cassette loader device 100 while stored in a cassette holder 10. Then one side of the tape cassette C is lifted from the cassette holder 10 by an arm and then a traveling body 120 is moved laterally to press the tape cassette C after the recording or reproduction onto an unloading tray 130, thereby completing a series of operations. Thus, the tape cassette C after use is unloaded to beside the cassette loader device. Consequently, the device becomes thin, several decks can be stacked vertically, and the installation area of the decks becomes small.