PURPOSE: To provide the small-sized tape cassette which is suitable for storing and carrying by miniaturizing the tape cassette.

CONSTITUTION: The tape cassette which houses supply and take-up reels 45, 44 wound with a magnetic tape 46 in a cassette housing has tape holders 19, 20 forming an aperture through which tape guides for drawing out the magnetic tape intrudes into the spacing between the magnetic tape and the reels. These holders are constituted integrally with a sliding body 18 slidable within the cassette housing. The tape holders are constituted to be movable between a first position where the holders are housed in the cassette housing and a second position where the holders project from the cassette housing and form the aperture. The cassette housing is provided with friction bodies 21, 22 which move integrally with the sliding body, regulating parts 23, 24 which are provided nearly parallel with the moving direction of the friction bodies and fitting grooves 2, 3 which have the slopes having a prescribed angle with the moving direction of the friction bodies. The friction bodies, the regulating parts and the slopes of the fitting grooves come into contact with the cores of the above- mentioned reels and rotate the cores of the reels in the taking-up direction of the tape when the tape holders move from the second position to the first position. The slackening magnetic tape is then reeled up by the movement of the tape holders.