PURPOSE: To obtain good fixation with reference to various kinds of transfer material by providing a means for changing a nip width between a fixing roller and a pressure roller and changing the nip width in accordance with the kinds of the transfer material.

CONSTITUTION: A pressure lever 5 is mounted so that the one end side of the lever 5 can be turned by a supporting shaft 6, and the pressure roller 2 is held in a state where the pressure roller 2 is pressured by the fixing roller 1 by a pressure cam 7 provided on the other end side of the lever 5, and then, a desired nip width can be given. When a mode is a special move, the pressure cam 7 is rotated so that the part 7a having a more projecting quantity may be made to abut on the pressure lever 5 and the pressure lever 5 may be pushed up around the supporting shaft 6, and then, the nip width between the fixing roller 1 and the pressure roller 2 can be increased. And furthermore, the set temperature of a heater 3 for the fixing roller 1 is increased about by 10°C, and also, the heater 4 for the pressure roller 2 is turned on. By controlling in such a way, optimum fixing conditions for giving satisfactory thermal energy in the case that a thick paper and an OHP sheet, etc., are applied for the transfer material are set.