Abstract: A disc cartridge includes a cartridge main body 2, a rotation wheel 4 rotatably accommodated in the cartridge main body 2, a pair of shutter plates 5a, 5b interposed between a lower shell 7 and the rotation wheel 4 for releasing a first opening 24 of a lower shell 7 and a second opening 44 of the rotation wheel 4 in association with the rotation of the rotation wheel 4 when the first opening 24 coincides with the second opening 44, and a locking member 72 for prohibiting the rotation of the rotation wheel 4. The locking member 72 includes a locking portion 76 engaged with an engaging recessed portion 85 of the rotation wheel 4 for locking the rotation wheel 4 at a position where the shutter plates 5a, 5b close the first opening 24 and a first and second unlocking pieces 77, 78 for releasing the state that the locking portion 76 is engaged with the engaging recessed portion 85.