Abstract: High purity silicon usable for production of solar cells is easily produced with high production efficiency. In a rotary chamber (50) made of quartz, which is evacuated and filled with an hydrogen-argon atmosphere containing SiF4, a plasma area (60) is generated by supplying electric power from a coil (51) to decompose SiF4 and produce silicon as being fine powder particles. Fine particles of seed silicon (Si) in the rotating reaction chamber are picked up and transported upward by weirs (52), and then they can fall by gravity into the plasma area where silicon elements produced by decomposition of SiF4 are deposited onto surfaces of the silicon fine particles.