To improve a beat noise for a video signal by providing a reference frequency generation part, a control part on/off controlling the reference frequency generation part and a bias oscillation part transitive-excited oscillating a bias at a reference frequency.

The reference frequency generation part 11 raises the reference frequency synchronized with the video signal from an L level to a fixed value. The transistor of the bias oscillation part 13 oscillates at this frequency to generate a bias voltage. The bias voltage is boosted to a prescribed voltage by a bias oscillation transformer 14 and is shaped in waveform by a filter capacitor 18. The bias voltage is applied to a whole width erase head 16 and a sound erase head 17 erasing only a linear sound as an erase voltage, and respective erase currents raise to the fixed value at a prescribed slope angle to start tape erase. Simultaneously, the sound output voltage of the recording amplifier 19 of the linear sound is synthesized with the bias voltage by resistors 10, 20 to be applied to a sound magnetic head 15 recording the linear sound, and the linear sound is recorded on a tape.