PURPOSE: To prevent information recorded on a magnetic recording medium from being destroyed owing to switching between the recording and reproduction of a magnetic head by providing a constant potential element which are brought into contact with one-terminal sides of the 1st and the 2nd switching elements and fix the terminals at a specific voltage.

CONSTITUTION: One terminal of the magnetic head MH which performs recording and reproduction is connected to the collector of a transistor(TR) Q8 as the 1st switching element which is turned on during reproduction and the other terminal is connected to the collector of a TR Q9 as the 2nd switching element which is turned on during recording. Then, the emitters of the TRs Q8 and Q9 are connected in common and the common connection point is grounded through the parallel circuit of a Zener diode ZD1 as the constant voltage element and a capacitor C10. Then, the period wherein the 1st and the 2nd switching elements are both turned on at a specific potential to short-circuit both ends of the head when the head is switched between recording and reproduction is provided to prevent the discharging/charging current of the capacitor connected to the head from flowing to the head.