Patent ID: 6986479

Claim:
A magnetic tape cartridge comprising: a cartridge case consisting of an upper half and a lower half; a magnetic tape pulling-out port formed at a corner of side wall of said cartridge case; a curved door opening/closing said magnetic tape pulling-out port; a guide groove guiding said door to universally slide in the door's opening/closing directions; a door-side spring hooking portion protrusively provided with said door; a case-side spring hooking portion formed in an inner surface of said cartridge case; a tensile coil spring, of which one end of the tensile coil spring is hooked in said door-side spring hooking portion and the other end of the tensile coil spring is hooked in said case-side spring hooking portion, energizing said door to a closing position of said magnetic tape pulling-out port; and a spring putting platform provided neighboring said door-side spring hooking portion, and for receiving said tensile coil spring in a state in which said tensile coil spring is temporarily assembled on in said door-side spring hooking portion.