also to a negative terminal of a differential amplified 125 through the adder circuit 124 on the other hand the switching signal hsw delivered from the hsw shaping circuit 108 is supplied to a sampling pulse shaping circuit 126 and an offset switching pulse shaping circuit 127 the sampling pulse shaping circuit 126 forms sampling hold pulses b and c for sampling pilot signals of adjacent recording tracks and supplies the sampling hold pulse b to the sampling hold circuit 123 and the sampling hold pulse c to the sampling hold circuit 128 the offset switching pulse shaping circuit 127 forms offset switching pulse d having a period of a half period of the switching signal hsw and supplies the pulse d to an offset signal generating circuit 129 the offset signal generating circuit 129 generates an offset signal e for controlling the magnetic head so as to trace the recording tracks maintaining a predetermined relation with said recording tracks and supplies the offset signal e to the negative terminal of the differential amplifier 125 through the adder circuit 124 the above sampling hold circuit 123 sampling holds the output signal a of the pilot signal shaping circuit 126 in synchronism with the sampling hold pulse b delivered from the sampling pulse shaping circuit 126 and inputs the above output signal a to the positive terminal of the differential amplifier 125 the output signal of the differential amplifier 125 is delivered to the sampling hold circuit 128 the sampling hold circuit 128 sampling holds the output signal of the differential amplifier 125 in synchronism with the sampling hold pulse c delivered from the.