A high-frequency induction system can generally be achieved by detecting noise superimposed on AC power supply which might induce voltages exceeding the given break-down voltage of a switching device and in such cases by temporarily shutting off the power supply to the induction heating system. To implement this, a high-frequency induction heating system, according to the invention, is provided with a noise detector circuit connected to the output terminal of a rectifying circuit rectifying said input AC voltage. The noise detector is designed to detect noise pulses superimposed on an input AC voltage. The induction heating system of the present invention also includes means for disabling a switching device. The disabling means responds to detection of a noise pulse by the noise detector by disabling the switching device and whereby protects the circuit of the induction heating system.