A purpose of the present invention is to provide an inverter circuit capable of suppressing an overshooting phenomenon of an input current at an instantaneous time when an initiating operation of the inverter circuit is switched to the normal operation thereof, and thus, capable of preventing damages of IGBTs and a magnetron.In a high frequency heating apparatus comprising: a control signal forming circuit for forming a control signal from a difference between an input current of an AC power supply and a reference current; a frequency modulated signal forming circuit for correcting rectified voltage/rectified current which are obtained by rectifying the AC voltage/current of the AC power supply based upon the control signal of the control signal forming circuit; and a dead time forming circuit for receiving the output of the frequency modulated signal forming circuit, a control signal converting circuit having a function capable of further lowering the value of the control signal is provided between the control signal forming circuit and the frequency modulated signal forming circuit.