PURPOSE: To make resistance values of both heating circuit patterns to correspond to each other, and make equal heating quantity of both unit heaters against the supply capability by cutting short-circuit patterns except for a short- circuit pattern, which is positioned most far from a terminal, of each unit heater.

CONSTITUTION: A connecting piece 8 for connecting both unit heating elements 1a, 1b is formed in a part, where conductive wire patterns 5 are formed, of an insulated board 2. This connecting piece 8 is folded at two parts to arrange both the unit heater 1a, 1b in the direction transverse to the longitudinal direction of a heating sheet A. In a corner part of the unit heater 1b different from the connecting piece 8, a notch 9 is formed so as to cut the intermediate part of the conductive wire pattern 5, and terminal wires 10 are respectively connected to parts of the conductive wire pattern 5 facing to the notch 9. Furthermore, short-circuit wire patterns 6 connected to the conductive wire pattern 5 are cut by punching or the like.