PURPOSE: To obtain continuous long-sized cylindrical room temperature setting(RTV) silicone foam, by injecting a RTV silicone foam material in a mold, in which a cylindrical center core covered with plastic film on its surface is supported with a plurality of center core fixing pins and heating the mold.

CONSTITUTION: A cylindrical center core 4 is arranged within a mold composed of a bottom force 1 and top forces 2, 3 being dividable into two. The center core 4 is supported with adequately spaced center core fixing pins 5 within the mold, a plurality of pins 5 being arranged in the long direction. The center core 4 is covered with a plastic film 6. The upper mold 2 is moved as shown by the top force 2' to open the mold, fire retardant RTV silicone foam material is put into the mold and the mold is heated by an electric heater 7 to foam said material. After being hardened, the produce is taken out from the mold and the center core 4 is drawn out to obtain a cylindrical fire retardant RTV silicone foam. The center core 4 is easily drawn out because the plastic film is not bonded to the product. Also a continuous long sized product without eccentricity can be obtained.