PURPOSE: To prevent a couple of rollers from being contaminated with a developer by disabling jamming paper from being extracted speedily at the time of jam processing.

CONSTITUTION: The device is equipped with a heat roller 1 and a pressure roller which contacts the heat roller 1 and rotates together with it. Then, a transfer material which carries an unfixed developer is passed between those heat roller 1 and pressure roller to fix the unfixed developer on the transfer material thermally. In this case, brake means 16, 18, and 20 apply braking forces to part of a roller driving system associatively with the operation in the jam processing. The jamming paper is disabled to be extracted speedily at the time of the jam processing. Consequently, the roller couple can be prevented from being contaminated with the developer.