PURPOSE: To effectively prevent the disconnection of the connecting part of a conductor pattern connected to one end part of a heating resistor, with a simple constitution.

CONSTITUTION: In this fixing heater provided with a substrate 11 consisting of the front side of a heat-resistant electrically insulating material, the heating resistor 12 formed on the surface 11a of the substrate 11 and a front side power feeding terminal part 13a in one end part and a front side conductor pattern 14 formed on the surface 11a of the substrate 11 and electrically connected to the other end part 12b of the heating resistor 12, the width Wa of the connecting part 14a connected to the heating resistor 12 of the front side conductor pattern 14 is made larger than the width Wb of the top end part 14b further ahead of the connecting part 14a.