A disk storage apparatus includes: an actuator positioning a head with respect to a disk; a drive device driving the actuator; a voltage detection device detecting a voltage signal induced in driving the actuator; a disturbance estimation unit estimating the magnitude of load disturbance exerted on the head from a drive signal and the voltage signal, and outputting a disturbance estimation signal; a filter unit cutting off a high frequency component of the disturbance estimation signal, and outputting a filter signal; a position detection unit producing a position error signal corresponding to a current position of the head; a position control unit producing a position control signal based on the position error signal; and a correction unit outputting the drive signal based on the filter signal and the position control signal, and the apparatus controls stable positioning of the head against a resistance value fluctuation of a drive coil of the actuator and a resistance value change.