PURPOSE: To prevent the damage of a temperature sensor of a coffee roaster, and to minimize the loss of heat through the front door of the roaster, by attaching a temperature sensor to the front door with a heat-insulating, elastic supporting means.

CONSTITUTION: Coffee beans are charged into a rotary drum 2 having perforations 22 and driven with a motor 4, and roasted with hot air heated with a heater 8 and sent into the drum 2 with a fan 11. The front door 7 of the drum 2 is furnished with a temperature sensor 5 supported with a heat-insulating, elastic supporting means 6. The temperature of the coffee beans is determined directly during the roasting, and the heater 8 is controlled according to the temperature.