PURPOSE: To smoothly move a shutter by providing tape guide parts in four places and providing these tape guide parts with an extended part forming the same plane as a shutter inserting recessed part where a shutter main body is slid to move.

CONSTITUTION: A magnetic head entering part, etc., are formed in a front surface of a cassette tape main body 100 of a combination of an upper part cassette half 310 and a lower part cassette half 110. The half 310 is provided with two inner side tape guide parts 410 and two outer side tape guide parts 420. Similarly, the half 110 is provided with four tape guides as well. The guides 410 and 420 have the extended part at the same level as the shutter inserting recessed part where the shutter 250 is slid to move back and forth. The inner side surface of the shutter 250 is brought into contact with this extended part on its outer surface, so that the shutter 250 is reinforced in the direction of its thin wall, and the shutter 250 projected out to cover over the recessed part of the magnetic head entering part, etc., is prevented from being distorted due to external force.