Disc cartridge including an inner shell formed by severing a molded portion and a flanged thin-walled section

A disc cartridge comprising:

• a disc-shaped recording medium;
• a main cartridge body unit including an upper shell and a lower shell, said main cartridge body unit accommodating said disc-shaped recording medium for rotation therein,
• wherein a peripheral wall section of said upper shell and a peripheral wall section of said lower shell abut against each other, and at least a portion of the peripheral wall section of said lower shell being opened to form an open end, with an aperture being formed in said main cartridge body unit beginning from said open end for exposing a portion of said disc-shaped recording medium to outside across the inner and outer rims of the disc-shaped recording medium;
• an inner shell engaged in a guide groove formed between an outer peripheral wall section and an inner peripheral wall section of said upper shell so as to be supported for rotation therein, said inner shell including a connecting portion engaged in said guide groove, said inner shell also including an aperture in register with said aperture in said main cartridge body unit;
• and
• a shutter member movable by rotation of said inner shell between a position closing said aperture in said main cartridge body unit and a position opening said aperture in said main cartridge body unit,
• wherein said inner shell includes a first molded portion, provided with a recording and/or reproducing aperture, a second molded portion having a resin injection port and molded at a position where said aperture is formed, and a flanged thin-walled section connecting said first and second molded portions to each other.