PURPOSE: To prevent the heap-up of resin at the end of a plunger when resin is cast in molds via a resin supply hole in an indexing table by the plunger from below the table and the plunger is separated from the table in the injection molding by indexing a plurality of the molds by an indexing unit.

CONSTITUTION: A plunger 16 is formed in a piston state, and a pressure release hole 24b is brought into coincidence with a resin inlet 16c at its lowered position. A shutter 26 is provided. When the shutter 26 is closed, a shutter hole 26c is opened to diffuse the air to the hole 26c. Thus, the resin in the resin supply passage 16b of the plunger 16 released from its pressurized state is moved from the resin inlet 16c to the hole 24b, and the heap-up of the resin to the plunger end 16a is eliminated. Since there is the shutter 26, the resin is not transferred to the plunger end 16a at the start of lowering of the shutter 26.