According to one embodiment, a disk device includes a base, a discoidal recording medium including an innermost circumferential portion and an outer circumferential edge, a head, a head actuator provided pivotably on the base and supporting the head movably, a first sensor which detects a shock and a drive unit which pivots, when the shock detected by the first sensor is greater than a predetermined value and the head is located at a position less than a predetermined distance from the innermost circumferential portion, the head actuator to place the head at a position more than the predetermined distance which satisfies a conditional formula below. D = 9.83 ⁢ e - 210 ⁢ t 2 G