An improved method is provided for the deposition of high-purity silicon on silicon particles from silicon source gases in a fluidized bed reactor which is divided into a heating zone and a reaction zone by a partition. Silicon particles in the heating zone are fluidized by a carrier gas such as hydrogen and are heated by microwaves. On the other hand, the reaction zone for the deposition of silicon, through which reaction gases including the silicon source pass, is heated by particle mixing between the reaction zone and the upper section of the heating zone. Subsequently, a desired reaction temperature at the reaction zone is maintained stable without deteriorating the microwave heating of the heating zone.