MAGNETIC TAPE CASSETTE

PROBLEM TO BE SOLVED: To prevent the infiltration of dust, foreign matter, etc., from an aperture formed when a slider exists in an advance position and to sufficiently assure a take-up region of a magnetic tape of the maximum possible extent by providing the cassette with dustproof walls formed by extending the rear ends of engaging slide parts of the slider toward the rear side-walls of a lower half. SOLUTION: The slider 2 has a base surface 3 and sidewalls 4a and 4b and has guide holes 5a and 5b corresponding to drive shaft insertion holes of supply side and rewinding side hubs of the lower half on the base surface 3. Engaging slide parts 6a and 6b of a long side form are disposed on the inner edge at the top ends of the sidewalls 4a and 4b. The rear surfaces 7a and 7b of the engaging slide parts 6a and 6b are engaged and brought into sliding contact with the front surfaces of the right and left sidewalls of the lower half. The rear ends of the engaging slide parts 6a and 6b are extendedly provided with the dustproof walls 9b and 9b toward the rear sidewall of the lower half. The dustproof walls 9b and 9b close the spacing formed between the lower half and an upper half and prevent the infiltration of the dust and foreign matter.