An image heating apparatus includes: an endless belt; a heater, contacted to a surface of the endless belt, provided so that a longitudinal direction thereof is parallel to a generating line direction of the endless belt; and a pressing member for forming a nip together with the endless belt. The heater includes: an elongated substrate; a first heat generating line, provided on the substrate along a longitudinal direction of the substrate, including first heat generating resistors having a negative temperature coefficient of resistance and being electrically connected in series; and a second heat generating line, provided on the substrate along the longitudinal direction of the substrate, electrically connected to the first heat generating line in parallel. The second heat generating line includes a plurality of second heat generating resistors having the negative temperature coefficient of resistance and being electrically connected in series.