NOVELTY - Manufacture of silicon involves supplying raw material (2) containing mixture of silica powder and graphite powder into container (12) containing refractory material including silica, heating graphite powder by absorbing microwave energy during irradiation of the microwave, such that temperature is increased, carrying out reduction reaction of silica, contacting produced silicon oxide gas with silica and/or graphite without dispersing silicon oxide gas out of the container (12), then, reducing silica by gas-solid reduction reaction, and continuously producing molten silicon (3).    USE - Manufacture of silicon used for semiconductor substrate and solar cell.    ADVANTAGE - The high-purity silicon is efficiently and economically manufactured, in short time.    DETAILED DESCRIPTION - Manufacture of silicon involves supplying raw material containing mixture of silica powder and graphite powder, or mixture of silica powder, silicon carbide powder and graphite powder into container (12) containing a refractory material including silica or silicon carbide, irradiating a microwave to the raw material in the container (12), and discharging molten silicon from the container (12). During microwave irradiation process, graphite powder is heated by absorbing microwave energy obtained by irradiation of the microwave, such that temperature is increased, reduction reaction of silica, silicon carbide and/or graphite is carried out, silicon oxide gas is produced as an intermediate product, produced silicon oxide gas is contacted with silica, graphite and/or silicon carbide without dispersing silicon oxide gas out of container (12) containing refractory material, then, silica is reduced by gas-solid reduction reaction, and molten silicon is continuously produced. An INDEPENDENT CLAIM is included for microwave reducing furnace, which has reactor containing container (12) which can prevent dispersion of generated gas while storing raw material, supply portion (14) which supplies raw material in container (12), discharge portion (13) which discharges the molten silicon after reduction from container (12), and microwave oscillator (33) which irradiates microwave having directivity by helical antenna (34) or waveguide toward the container (12).    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the microwave reducing furnace used for manufacture of silicon. (Drawing includes non-English language text)    Raw material (2)    Molten silicon (3)    Container (12)    Discharge portion (13)    Supply portion (14)    Microwave oscillator (33)    Helical antenna (34)