Abstract: The present invention provides an improved positioning control system for a hard disk device, wherein a servo burst signal for the head positioning is stored at two points on the circumference of each track of the disk in order to eliminate the recording density, thereby performing fine positioning of a two phase step motor by microstepping. The step motor is connected to a rotary type actuator through a steel belt, thereby moving the head in a radial direction along the disk by driving the step motor. The step motor is excited every .pi./4 (rad) of the two phase electrical phase angle from a positon of .pi./8 (rad) of the two phase electrical phase angle, at the time of exciting. The measurement of the hysteresis of the step motor and the measurement of an off-set value of the step motor are performed at the time of excitement the device, thereby realizing the correction of the measurement of track head deviation from a track center during operation.