To provide a rapid thermal processing reactor which can handle wafers of multiple sizes and can heat them to an almost uniform temperature in the process.

A rapid thermal processing (RTP) reactor 300 uses one or two heat sources 310 to process multiple wafers 311 and 312 or a single large wafer. The single wafer is or the multiple wafers 311 and 312 are placed on a rotatable susceptor 302 supported by a susceptor support 304. A susceptor control unit rotates the wafers 311 and 312 in the process, and raises/lowers the susceptor 302 at various positions where the wafers 311 and 312 are loaded and processed. A thermal control unit controls the one or two heat sources which heat the wafers to an almost uniform temperature in the process. A gas flow control unit controls gas flow into a reaction chamber.