A lever and a weight are supported on a first shaft for swinging movement in a latch mechanism. The weight gets closer to a head actuator member based on swinging movement in a first direction. A restriction member restricts the swinging movement of the weight in a second direction opposite to the first direction. A swinging member is contacted with the lever swinging around the first shaft so that the swinging member gets into a predetermined path of the head actuator member through the swinging movement around the second shaft. The disk drive always allows the weight, the lever and the swinging member to start swinging from corresponding inoperative positions, even if the disk drive suffers from a sequential driving force in opposite directions due to impact. A head slider at the tip end of the head actuator member is reliably prevented from colliding against the disk.