PURPOSE: To deal with any arbitrary horizontal cycle with high efficiency without generating jamming signals to appear on the screen of a display device.

CONSTITUTION: A variable inductance coil 14 and a deflecting transformer 6 are serially connected, a current to flow to a horizontal deflecting coil 4 is detected by a current detection circuit 7 serially connected to the horizontal deflecting coil, and this horizontal deflecting current is fed back by a variable inductance coil control circuit composed of a comparator 10, drive circuit 11 and drive transistor 12. Then, the inductance value of the variable inductance coil 14 is changed, a voltage in charge of the deflecting transformer 6 is changed, and the horizontal deflecting current is kept constant.