The present invention is relative to a disc cartridge in which an optical disc (3), an inner shell (4) and shutter members (5a), (5b) are housed in a main cartridge body unit (2), formed by abutting and combining upper and lower shells (6), (7), and in which the inner shell is run in rotation to cause the shutter members (5a), (5b) to open or close an aperture (24) provided in the main cartridge body unit (2). On an inner side of the peripheral wall sections of the upper and lower shells, abutted to each other, a crank-shaped dust intrusion prohibiting unit (21A) is provided for prohibiting intrusion of dust and dirt from the abutting surfaces of the peripheral wall sections of the upper and lower shells towards the optical disc housed in the main cartridge body unit to protect the optical disc housed in the main cartridge body unit. The inner shell provided in the main cartridge body unit includes an aperture (44) in register with an aperture in the main cartridge body unit, and includes a connecting portion (43a) bridging an open end side of the aperture. This connecting portion has a height not protruding towards the lower shell.