Magnetic tape cartridge

A magnetic tape cartridge comprising:

• a single reel with magnetic tape wound thereon;
• a cartridge case, which comprises an upper case and a lower case, for rotatably housing said single reel;
• and
• a write protection member for inhibiting magnetic recording onto said magnetic tape, slidably disposed within said cartridge case, further comprising
• a sliding main body,
• a control portion provided on an outside surface of said sliding main body so that it is movable between a first position of enabling said magnetic recording and a second position of inhibiting said magnetic recording, while facing a control window formed in a side surface of said cartridge case, and
• a protrusion, provided on a bottom portion of said sliding main body, which is inserted into a bottom hole formed in a sliding direction of said sliding main body in a bottom wall of said lower case and movable within said bottom hole;
• wherein a stopper piece is provided on an inside surface of said sliding main body so that it protrudes in a direction perpendicular to said sliding direction;
• wherein an elastically deformable guide wall is formed along said sliding direction in said cartridge case and has a first stopper groove and a second stopper groove at positions corresponding to said first and second positions;
• and wherein said stopper piece is fitted in said first or second stopper groove and holds a stopped position thereof.