A new cassette tape player is provided. It comprises a cassette holder, an actuator arm pivotally disposed within the chassis, a slide plate which moves with the rotation of the actuator arm, a hook plate to lock the slide plate at a locking position, and a cassette positioning lever to rotate upon completion of actuator arm to ensure that the cassette received in the cassette holder is properly positioned. The hook plate is also provided with means for damping a shock inflicted thereon.