A head support device is thin and assures excellent flexibility and shock resistance while applying a sufficient load to a head. A disk drive uses the head support device. The head support device comprises a support arm, a head disposed at one end of the support arm, which is mounted on a head slider so as to be opposed to a recording medium, an elastic member such as a plate spring which provides the support arm an activating force in a direction perpendicular to the recording medium when the support arm comes to a rotational center in vertical rotation against the recording medium, and a holder connected to the elastic member. When an external impact force is applied to the head slider, with a distance from an action point of load that activates the head slider toward the recording medium to an immovable point in the rotation of the head slider in a direction of pitch being Lo, and a length of head slider in a direction of air flow being Ls, then 0.5