A disc cartridge accommodating an optical disc in a cartridge body. The disc cartridge includes a cartridge body formed by mating and joining upper and lower halves mated together. A plurality of fusing portions for mating and fusing the upper and lower halves are provided at positions corresponding to recess portions for accommodating an optical disc. Each fusing portion is provided with a mating projection formed at one of the upper and lower halves and a mating projection formed at the other of the upper and lower halves. A plurality of mating projections formed at either half comprise mating projections having projections for fusing annularly and continuously formed over the entire circumference of the end surfaces to be mated to the mating projections of the other half and mating projections having projections for fusing formed in the form of an arc in one part of the end surfaces.