A silicon production process which improves the production efficiency of trichlorosilane while an industrially advantageous output is ensured and the amount of the by-produced tetrachlorosilane is suppressed. This process does not require a bulky reduction apparatus for the by-produced tetrachlorosilane, can construct a closed system, which is a self-supporting silicon production process, can easily control the amount of the by-produced tetrachlorosilane and therefore can adjust the amount of tetrachlorosilane to be supplied to a tetrachlorosilane treating system when the tetrachlorosilane treating system is used. This process comprises a silicon deposition step for forming silicon by reacting trichlorosilane with hydrogen at a temperature of 1,300 C. or higher, a trichlorosilane forming step for forming trichlorosilane by contacting the exhausted gas in the above silicon deposition step to raw material silicon to react hydrogen chloride contained in the exhausted gas with silicon, and a trichlorosilane first recycling step for separating trichlorosilane from the exhausted gas in the trichlorosilane forming step and recycling it to the silicon deposition step.