Heat roller type fixing apparatus

A heat roller type fixing apparatus having a heat roller accommodating a heating element and adapted for fixing a toner image to a copying paper, a temperature sensing element for sensing the temperature of the heat roller surface and a control circuit adapted to cooperate with the temperature sensing element in controlling the heat roller surface temperature. The heat roller and the heating element are so arranged, in the temperature rising period from the start of the power supply to the heating element till the heat roller surface is heated up to a set temperature, that the highest roller surface temperature is observed at portions of the heat roller between the center and both axial ends of the roller, and that the temperature sensing element is disposed on or in the close proximity of one of the portions of the highest roller surface temperature. The temperature sensing element is a thermocouple stretched along the portion of the heat roller of the highest temperature in the axial direction of the roller and slightly apart from the surface of the roller.