PURPOSE: To smoothly fill a hot-melt resin material without lowering the viscosity of the material and to eliminate frothing by horizontally reciprocating a gun nozzle or a forming die when the material is injected and filling the material uniformly in the die.

CONSTITUTION: A resin injector 1 is reciprocated to the left and right by a reciprocating cylinder 1 to inject a hot-melt resin material 4' into a forming die 5 from a gun nozzle 3. In this case, as for the injector 1, a seat plate 9 is arranged on a couple of rails 7 laid over the upper face of a table 6 through a slide guide 8. The cylinder 2 is fixed to the upper face of the table 6, and a cylinder rod 10 is fixed to the seat plate 9 through an L-shaped bracket 11. The die 5 is fixed to a conveyor belt 14 on the upper face of the table 6, the belt 14 is driven in the longitudinal direction of the rail 7, and the gun nozzle 3 is projected from the tip of a hot melt gun 20 fixed to the main body frame 21.