Magnetic disk cartridge

A magnetic disk cartridge comprising a cassette shell, which is constituted of a pair of cassette shell halves joined to each other, and a magnetic disk incorporated in the cassette shell such that the magnetic disk can rotate, wherein:

• the pair of the cassette shell halves are provided with contact surfaces on their inner surfaces, which contact surfaces come into contact with each other when the cassette shell halves are temporarily assembled to each other,
• one of the cassette shell halves is provided with a cylindrical body, which protrudes from said one cassette shell half toward the other cassette shell half, said cylindrical body having a rivet press-fit hole constituted of a through hole, into which a temporary securing rivet is to be press-fitted, said cylindrical body being constituted of a plurality of elastic engagement pieces divided from one another by a plurality of slits, which are formed in the wall of said cylindrical body and extend along the axial direction of said cylindrical body,
• said other cassette shell half is provided with an opening for rivet insertion, which opens to an outer surface of said other cassette shell half, and an engagement piece receiving hole, which receives said elastic engagement pieces, said engagement piece receiving hole communicating from said opening for rivet insertion to the inner surface of said other cassette shell half, an inner wall surface of said engagement piece receiving hole forming a tapered surface, the diameter of which is increased from an end, that stands facing said one cassette shell half, toward said opening for rivet insertion, and
• in a state in which said elastic engagement pieces have been inserted into said engagement piece receiving hole and said contact surfaces of the pair of the cassette shell halves have been brought into contact with each other, said elastic engagement pieces are brought into pressure contact with and engaged with said tapered surface of said engagement piece receiving hole by said temporary securing rivet, which is press-fitted through said opening for rivet insertion and into said rivet press-fit hole, whereby the pair of the cassette shell halves are temporarily assembled to each other.