To perform miniaturization and to provide the fly-back transformer of the wide variable adjustment range of a voltage.

This transformer is provided with a first transformer part 22 for supplying an anode voltage 31 to a cathode-ray tube 21, a voltage variable adjustment circuit part 23 for varying and supplying a focus voltage 32 or a screen voltage 33 to the cathode-ray tube 31 and a second transformer part 24 for supplying an output voltage to the voltage variable adjustment circuit part 23. The first transformer part 22 and the second transformer part 24 are respectively provided with primary coils 25 and 26 and secondary coils 27 and 28 and they are not shared with each other.