A disc cartridge having a disc-shaped recording medium, such as an optical disc or a magneto-optical disc, rotatably housed within a main cartridge body. The disc cartridge has a main cartridge body made up of an upper cartridge half and a lower cartridge half, and a disc-shaped recording medium rotatably accommodated within the main cartridge body. A recording and/or reproducing aperture is formed in at least one of major surfaces of the main cartridge body. A shutter is mounted for movement along a sidewall section of the main cartridge body between a position closing the aperture and a position opening the aperture. There is provided an inclined portion in the aperture inclined with respect to the inserting direction of the disc cartridge.