A center distance between heating rollers for suspending an external heating belt is fixed, and a peripheral length of the external heating belt is set so that a tension is not exerted to the external heating belt when the external heating belt is not pressed against the fixing roller and the tension is exerted to the external heating belt when the external heating belt is pressed against the fixing roller. As a result, it is possible to provide an external belt heating type fixing apparatus, having a simple arrangement, which is excellent in a thermal efficiency and can suppress snaking of the belt.