this invention relates to an induction heating apparatus including a digitized control circuit and digitizing the on / off control circuit for a switching element which has hitherto utilized the r - c time constant , thereby eliminating the defects , such as a change in the r - c time constant with the time ageing and non - stabilization of the heating output accompanied by a temperature change . since the digitized control circuit can be a monolithic integrated circuit , the apparatus as a whole can be miniaturized or smaller in thickness and inexpensive to produce . furthermore , the induction heating apparatus realizes by the digitized control circuit quick overcurrent protection , exact detection of unsuitable load , prevention of noise generation , and facility of design corresponding to various power supply voltage .