PURPOSE: To take out or insert a tape cassette smoothly by constituting an opening to take out or insert a tape cassette on two side surface parts which are adjacent.

CONSTITUTION: A tape cassette storage case (so called sleeve) S is constituted with a right side plate part 1, a left side plate part 2, a back plate part 3 and a bottom palate part 4, and a front plate part and an upper plate part are constituted into an opening parts 5, 6, and a tape cassette T can be taken out or inserted from these two opening parts 5, 6. Notches 7a, 7b, 8a, 8b are formed at end parts of the right side plate part 1 and left side plate part 2. When the tape cassette T is taken out or inserted to the sleeve S, taking out or insertion of the tape cassette T can be done not only from the front side but also from the top side or diagonally from the upper side, and the degree of freedom for taking out or insertion is higher for that reason, and taking out or insertion of the tape cassette T becomes easier.