A heating device and an image forming apparatus which make it possible to improve the degree of freedom in design to enhance the accuracy of detecting the state of a to-be-heated member, and easily reduce cost. An induction heating coil generates magnetic flux by flow of electric current therethrough. Ferrite cores formed of a magnetic material form magnetic paths. The fixing belt generates heat by the action of the magnetic flux generated by the induction heating coil 101. An antenna is disposed in an area at a location opposite to the fixing belt 120 with the ferrite cores therebetween, for detecting magnetic flux passing through the area. A control circuit determines whether or not the state of the fixing belt has changed, based on a result of detection by the antenna.