Abstract: An automatic disk cassette changing apparatus employs a pair of cassette storage racks for holding a plurality of optical disk cassettes in an upright (vertical) position. A motor operated loading mechanism checks to see if an operator has properly loaded a cassette onto a transport slide and then moves the slide to place the cassette in a predetermined position inside the apparatus. A cassette handling mechanism including a tiltable carrying frame then picks up the cassette and delivers it either to a storage slot in one of the storage racks or to an optical read/write unit. To insert a cassette into the latter, the carrying frame is tilted 90 degrees so that the cassette is loaded into the read/write unit in approximately a horizontal position. The handling mechanism employs three separate motors for raising and lowering the carrying frame, for tilting the carrying frame, and for moving the frame from side-to-side in response to control commands.