A signal is sent to a deflection circuit and a video signal processing circuit. On receiving the signal, the deflection circuit outputs a vertical deflection signal and a horizontal deflection signal. The vertical deflection signal is sent directly to a deflection yoke while the horizontal deflection signal is sent via an S-shaped wave modulation circuit to the deflection yoke. On the other hand, the video signal processing circuit receives the signal and outputs a video signal via an amplitude modulation circuit and a frequency modulation circuit to a cathode of an electron gun. The S-shaped wave modulation circuit performs modulation on the horizontal deflection signal to change scanning speed. The amplitude modulation circuit and the frequency modulation circuit perform, on the video signal, amplitude modulation and frequency modulation which are appropriate for this speed.