PURPOSE: To execute adequate drying in compliance with contents by measuring the temp. distribution of the contents in a housing by a pyroelectric type IR sensor for detecting IR rays to detect the degree of drying and controlling the operation of a main body of a drying machine in accordance with the detection output.

CONSTITUTION: A rotary drum 3 and fan 4 disposed in one side part of the main body 1 of the drying machine are respectively rotationally driven via plural belts 5, 6 by a motor 2 disposed in the bottom. A heater 7 of a heating source is disposed in the other side part of the main body 1 of the drying machine. In such a case, the IR sensor 9 detecting IR rays is installed to the inner side of a cap 8 disposed at the main body 1 of the drying machine so as to cover the aperture of the rotary drum 3. The operation of the main body 1 of the drying machine is controlled in accordance with the detection signal of the IR sensor 9. The IR sensor 9 is composed of a pyroelectric type and plural pieces of such sensors are disposed. In addition, the difference between the detection outputs is used as an operation stop signal or the difference between the value of this time and the value of the previous time of the detection outputs is used as the operation stop signal.