Method of producing a silicon compound material and apparatus for producing a silicon compound material

A method of producing a silicon compound material, comprising:

• storing a silicon carbide preform in a reaction furnace;
• supplying a raw material gas containing methyltrichlorosilane to the reaction furnace to infiltrate the preform with silicon carbide;
• and
• reducing a temperature of a gas discharged from the reaction furnace to a predetermined temperature at a predetermined rate while adding an additive gas to the gas discharged from the reaction furnace, and subsequently retaining the temperature of the gas to which the additive gas has been added at the predetermined temperature, thereby decreasing generation of a liquid or solid by-product derived from the gas discharged from the reaction furnace.