PURPOSE: To aways keep good rising and falling characteristics of a writing current and also to attain reduction of a power consumption at the normal driving by providing a voltage control means and controlling the driving voltage as required.

CONSTITUTION: A differential signal E of rise detection output of a signal A is produced by a D-type FF 1 to which a data signal A and clock signal C are supplied, and an AND gate 3 of the voltage control circuit to which the Q output of FF 1 is supplied, and similarly a differential signal F of fall detection output of the signal A is formed. P-type transistors 18, 21 are made ON through AND gates 6, 9 forming the voltage control circuit by these signals E, F together with the gate 3 and an AND gate 4, then a magnetic head 24 which is driven in low voltage by a 2nd voltage source VCC 2 at the rise/fall time of signal A and a 1st voltage source VCC 1 at the normal driving time, is driven with high voltage. By this procedure, the rise and fall characteristics of writing current are made good, and the power consumption at the normal driving time is also reduced.