PURPOSE: To obtain an apparatus which can heat-treat a wafer uniformly without stopping and readjusting the apparatus even when the size and the heat-treatment temperature of the wafer are different by including a mechanism which can change the distance between the wafer and a heating lamp according to a treatment temperature while the distance between the wafer and a radiation thermometer is kept definite.

CONSTITUTION: The apparatus includes a heat-treatment chamber 2; a gas supply device 11 which supplies a gas to the heat-treatment chamber 2; a unit which includes a radiation thermometer 5 used to measure the treatment temperature of a semiconductor wafer 1 and installed so as to fix the relational position between a semiconductor- wafer support pin 10 supporting the semiconductor wafer 1 in a prescribed state and which is installed at the lower part of the heat-treatment chamber 2; a heating lamp 3 which heats the semiconductor wafer 1; and a mechanism 11 which can change the distance between the semiconductor wafer 1 and the heating lamp 3 while the distance between the semiconductor wafer 1 and the radiation thermometer 5 is kept definite. For example, the unit is moved up and down by using a semiconductor-wafer elevator 11 so as to change the distance between a wafer 1 and a heating lamp 3.