PURPOSE: To perform glazing of powder paint and curing of coated film at optimum temp. by performing heating of material to be coated prior to glazing by induction heating at low frequency and performing at high frequency after glazing.

CONSTITUTION: An induction heating apparatus 2 for preheating at 50W500 cycle is provided to the fore position of a booth 1 in a painting line, and an induction heating apparatus 3 for post heating at 500W1,000 cycle is provided to the hind position of the booth 1. And, the heating of the object to be heated prior to glazing is performed with the induction heating apparatus 2, and the heating after glazing is performed with the induction heating apparatus 3. In this way, the temp. is controlled optimally and curing of paint film is performed.