A controller controls movement of a head mounted in a storage apparatus based on a signal output from an acceleration sensor. A head movement control section which controls movement of the head to a target position on a storage medium and a head unload control section unloads the head to an unload position based on (1) the time at which a drop or initial impact is first detected based on a signal output from the acceleration sensor and (2) threshold information, which includes a first threshold representing a standard strength of the signal output from the acceleration sensor at the time of drop and a second threshold representing a standard strength of the signal output from the acceleration sensor at the time of initially receiving impact.