PURPOSE: To improve the positioning and regenerating performance of a cassette to a device by deciding the front and back positions of a cassette main body when a pair of reference shafts have a contact with the cassette main body only at the lower half side of a pair of reference holes formed within the cassette main body.

CONSTITUTION: The rear sides of a pair of reference shafts 20 have contacts with contact faces 16a' and 116a', and the front and back positions of the half 3 are decided. In this case, the rear sides of a pair of shafts 30 have no contact with contact faces 36a' and 126a' of the half 3. The right and left positions of a cassette main body 1 are decided by a left reference hole 16. Then the front and back positions of the body 1 containing upper and lower halves are always decided by the shafts 20 or 30 only when the body 1 has a contact with the contact wall surface of the half 3.