PURPOSE: To suppress the fluctuation of coil currents, and to reduce the bending of a screen by providing a resistor between a diode at the secondary coil side of a correcting transformer and the low voltage side of the secondary coil of a main transformer in a fly-back transformer.

CONSTITUTION: A resistor 35 more than 30kΩ is connected between the low voltage side of a secondary coil 25 of a main transformer 22 and a rectifying diode 33b. Then, the regulation of a more static high voltage output voltage than conventional can be delayed corresponding to the response delay of a correcting transformer 29. Thus, the regulation of the dynamic high voltage output voltage can be satisfactory, and the fluctuation of the high voltage output voltage can be suppressed. Therefore, the current change of a primary coil 24 of the main transformer 22 can be suppressed, the currents flowing through the deflection coil 42 of a television receiver can be stable, and the bending of the screen can be reduced.