The present invention for eliminating a need for a temperature detecting element adapted to measure the temperature of a roll main body provides an induction heated roll apparatus including: a roll main body; a magnetic flux generating mechanism including an iron core and a winding; and a power supply circuit provided with a control element adapted to control AC current or AC voltage. The apparatus calculates the temperature of the roll main body using an AC current value obtained by an AC current detecting part, an AC voltage value obtained by an AC voltage detecting part, a power factor obtained by a power factor detecting part, a winding resistance value of the winding, and an excitation resistance obtained from characteristics of a relationship between a magnetic flux density and an excitation resistance of a magnetic circuit including the iron core and the roll main body as parameters.