PURPOSE: To provide the title filling machine constituted so as not generate the clogging of the gap between a piston and the inner wall of a raw material supply pipe with a raw material at the time of the retreat of the piston, miniaturized as a whole so as to reduce the stroke of a cylinder and capable of efficiently filling a foaming mold with the raw material.

CONSTITUTION: In a foam molding raw material filling machine wherein the piston 4 for opening and closing the opening part 2 for filling a mold with a pre-foamed granular raw material by the operation of a cylinder is provided to the rear of a raw material supply pipe 1 having the opening part 2 provided to the leading end thereof, an air passage 11 for injecting air for supplying the raw material to the opening part 2 from the front of the piston 4 in the back position and an air nozzle pipe 15 injecting air into the gap S between the piston 4 and the raw material supply pipe 1 from the rear of the piston 4 to prevent the clogging of the gas S with the raw material are provided in the raw material supply pipe 1.