It is possible to produce high purity Si by heating solid SiO at a temperature of at least 1000° C. and lower than 1730° C., for a disproportionation reaction in which the SiO solid is decomposed to liquid or solid Si and solid SiO2, and the produced Si is separated from the SiO2 and/or SiO. The SiO solid can be obtained by a process whereby a starting mixture of carbon C, silicon Si or ferrosilicon, or a combination thereof, with SiO2 is heated to generate SiO gas-containing gas, and the SiO-containing gas is cooled to produce SiO solid.