A compact size tape cassette including a pair of brake mechanisms associated with supply and take-up reel hubs for simultaneously locking the reel hubs in position against rotation relative to a housing. The brake mechanisms are interlocked such that a releasing operation of one brake mechanism is transmitted to the other brake mechanism for causing synchronized release of the brake mechanisms. The take-up reel hub is provided with annular flanges, and the brake mechanisms include abutments which selectively prevent locking pawls from moving into a space between the flanges. An oblique actuating surface is provided for contacting a brake releasing pin. The mechanisms further include an inspection and adjustment slot as well as a cam engageable by the supply reel hub for temporarily releasing the supply reel hub when the supply reel hub is lifted.