Abstract: In a heating fluid medium passing roller device for heat-treating a object to be processed in contact with the surface of a roller 1, heat exchanger devices 5a, 5b are arranged on a circulating heating fluid medium path, and the heating fluid medium heat-exchanged in the heat exchanger device is passed through the roller 1 having a jacked chamber 1b sealed with a gas-liquid two phase heating medium within its wall to keep the roller 1 at a predetermined temperature. Further, the heating fluid medium passing roller device includes a temperature sensor 13 for detecting the temperature of the heating fluid medium to be supplied into the roller 1 and a temperature sensor 14 for detecting the temperature of the heating fluid medium exhausted from the roller 1. The flow rate of the heating fluid medium to be supplied into the roller is adjusted so that the difference between the temperatures detected by the temperature sensors 13 and 14 is constant.