Abstract: An induction heating apparatus is disclosed which includes a high frequency power source having a leading phase angle setting circuit, which is supplied with a detection voltage signal from an output side of a high frequency inverter connected to a load circuit, to supply a leading phase angle signal to gates of thyristors of the inverter. The high frequency power source further includes a phase control circuit, provided after the voltage detection circuit, which is supplied with the detection voltage signal from the output side of the inverter to periodically control a phase of the detection voltage signal. The induction heating apparatus further includes a series inductor provided in between the power supply bus line connected to an induction heating coil wherein a magnetic member is provided to be inserted into and taken out of the inductor. A drive device is included for driving the magnetic member.