A rotating disk storage device has a mechanism for latching an actuator head suspension assembly (AHSA) positively in a retraction area upon occurrence of an external shock or runaway. In one embodiment, a latch mechanism comprises an AHSA which is supported pivotably, an elastic member which restricts a pivotal movement of the AHSA in a pivot direction A1 of the AHSA, an inertia member adapted to move pivotally in a corresponding pivot direction B2 when the AHSA moves pivotally in the pivot direction A1 while deforming the elastic member elastically, and a latch member having an engaging portion and adapted to move pivotally in a direction A2 opposite from the corresponding pivot direction B2 upon receipt of torque from the inertia member, thereby causing the engaging portion to move to a latching position. The AHSA has two to-be-engaged portions, i.e., a first to-be-engaged portion and a second to-be-engaged portion. Even in the event the engaging portion cannot engage the first to-be-engaged portion, it can engage the second to-be-engaged portion.