Abstract: Provided is a method for heat-treating a silicon wafer in an inert gas atmosphere, wherein it is possible to discharge SiO gas produced in melting a natural oxide film on the surface of the silicon wafer efficiently, to suppress the accumulation of reaction products in the heat treatment chamber, and to prevent slip deterioration. The wafer is held for a period of 5 to 30 sec inclusive, the rotational speed of the wafer is set to 80 to 120 rpm, and further the inert gas supply in the chamber is controlled so that the gas replacement rate is 90% or more in a temperature range of 900 to 1100° C. inclusive.