Method for manufacturing ceramic product containing silicon carbide

A sealing method for reducing an oxygen concentration in a furnace, comprising:

• preliminarily, a step of inspecting a leak of an inert gas in a continuous furnace from a furnace wall with a leak detector, and when the leak of the inert gas is detected by the leak detector, a step of performing a seal to prevent air from an outside of the furnace from flowing into an inside of the furnace at a leak location;
• and
• thereafter, performing a method for manufacturing a ceramic product containing silicon carbide, comprising a step of firing a formed body of a green body containing silicon carbide by transporting the formed body from an inlet to an outlet of the continuous furnace, wherein the continuous furnace comprises the inlet, a heating zone, a cooling zone, and the outlet in this order, and a furnace atmosphere in both the entire heating zone and the entire cooling zone is an inert gas having an oxygen concentration of 1 ppm by volume or more and 100 ppm by volume or less,
• wherein the cooling zone refers to a range in a traveling direction of the formed body from immediately after a heater provided closest to the outlet to the outlet of the continuous furnace, and the formed body is cooled to at least 530° C. in the cooling zone, and
• wherein the step of inspecting the leak of the inert gas in the furnace from the furnace wall with the leak detector is at least performed on a location where there is a component inserted into a through hole formed on the furnace wall and connecting the outside and inside of the furnace in the cooling zone.