A rotating disk storage device has a stopper mechanism and a latch mechanism for diminishing a shock imposed on an actuator head suspension assembly (AHSA) and permits positive retraction of the AHSA upon occurrence of an external shock or runaway. In one embodiment, the latch mechanism comprises an AHSA which is supported pivotably, a stopper which restricts a pivotal movement in a pivot direction of the AHSA, an inertia member adapted to move pivotally in a corresponding pivot direction when the AHSA moves pivotally in the pivot direction while causing the stopper to be deformed elastically, and a latch member which has an engaging portion and which, upon receipt of the torque from the inertia member, moves pivotally in a direction opposite from the corresponding pivot direction, and causes the engaging portion to move to a latching position. Shock energy of the AHSA is attenuated by both stopper and inertia member.