PURPOSE: To reduce the power consumption of a printer by heating a heat roller only at the area corresponding to the width of a printing paper used.

CONSTITUTION: The device is provided with a width detecting means 1 detecting the width of the printing paper P used, a controlling means 2 judging the paper width and instructing the heating area of the heat roller, and a heating area dividing type heat roller 3. The width is detected by the width detecting means 1 according to the feeding of the printing paper P used, and only the specified width of the heat roller 3 is heated through the controlling means 2 instructing the heating width based on a detecting signal. Thus, unnecessary power can be restrained when the printing paper having small width is used.