Support rollers suspending an endless belt are arranged so that a distance between each support roller and a fixing roller is smaller than a height of a belt regulating member provided on each side of the support roller in moving the support rollers to the second position which allows the endless belt to be in contact with the fixing roller so that a contact area therebetween is smaller than in the first position. As a result, in a fixing apparatus which includes the regulating member for regulating a position of an external heating belt in a rotational axis direction so that a contact area size between the external heating belt and the fixing member is variable, it is possible to appropriately vary the contact area between the belt and the fixing material.