To arbitrarily and precisely set the time during which a bias current flows for the magnetization reversal reset operation of a head.

A parameter set, which includes current value parameters and time parameters for every spin valve head 102, is registered in a flash ROM 113. During a pin reversal reset operation, a parameter set, which is peculiar to the head 102 that becomes an object, is selected and set in a regsiter group 109a of a head amplifier circuit 109. Then, the circuit 109 is set in a pin reversal reset mode and a clock generator 111d supplies a clock to the circuit 109. Then, the circuit 109 counts the clock by the number of the time parameters set in the group 109a using a counter 109b and causes a bias current having the current value shown by the current value parameter set in the group 109a to flow through the head 102 during the count interval of the number of the time parameters.