The invention prevents the deterioration of the read/write performance of a hard disk drive due to the interference between an inertial latching mechanism and an actuator when a head slider holding a magnetic head is located at a read/write position. A latching arm 22 provided with a projection 23 and included in an inertial latching mechanism 20, and a part 161 of a coil holding arm 16a included in an actuator are formed in shapes such that the latching arm 22 provided with the projection 23 does not interfere with the coil holding arm 16a having the part 161 when a head slider mounted on the actuator is located at a read/write position on a magnetic disk.