An image heating apparatus includes a belt member for heating an image on a recording material; a heater heating the belt member; a supporting portion, provided on an inner surface of the belt member, for detachably supporting the belt member; a temperature detecting member contacted to the inner surface of the belt member and elastically supported by the supporting portion; a controller for controlling energization to the heater on the basis of an output of the temperature detecting member; and an inclined surface, provided to the temperature detecting member, for guiding the temperature detecting member toward an inside of the belt member in contact with the belt member during a mounting operation of the belt member to the supporting portion.