An apparatus for producing trichlorosilane includes: a decomposing furnace, a heating unit heating the inside of the decomposing furnace, a raw material supplying tube for guiding polymer and hydrogen chloride to be guided to the inner bottom portion of the decomposing furnace, and a gas discharge tube for discharging reaction gas from the top of the reaction chamber provided between the outer peripheral surface of the raw material supplying tube and the inner peripheral surface of the decomposing furnace, a fin, which guides a fluid mixture of the polymer and the hydrogen chloride supplied from the lower end opening of the raw material supplying tube to be agitated and rise upward in the reaction chamber, and is formed integrally with at least one of the outer peripheral surface of the raw material supplying tube and the inner peripheral surface of the decomposing furnace.