PURPOSE: To surely engage and hold a lid in the manner of increasing the spring force of an arm to pressurize a lid lock and reducing the force for moving the lid lock by providing a spring fulcrum brought in contact part between a turning center of the arm of the spring and the contact part of the lid lock.

CONSTITUTION: The spring 25 provided with two arms 25a, 25b is interposed- between a cassette easing 1 consisting of a pair of upper half 1a and lower half 1b, wherein an information recording tape is housed, and the lid 12 for covering a part of the tape exposed to a mouth part 3 of the casing 1 so as capable of opening and closing. The lid 12 is pressed by one arm 25a of the spring 25 and also the lid lock 26 is pressed by another arm 25b to engage and hold the lid 12 by the lock 26 when the lid 12 is closed. The fulcrum D is provided for supporting the another arm 25b by bringing in contact between the turning center A of the another arm 25b of the spring 25 and the contact part C of the lock 26. Since the fulcrum for supporting the arm 25b is moved from the turning center A to the fulcrum D as the result that a rib 29 is arranged, the force exerted to the lock 26 from the arm 25b is increased, then the lid 12 is surely engaged and held.