PURPOSE: To prevent the stagnation of a resin in a nozzle part by simple constitution and to achieve certain operation.

CONSTITUTION: A nozzle 10 is formed to the cylindrical nozzle arranged between a fixed cylinder 20 and a fixed hollow sleeve 22 in a slidable manner and a pressure generating chamber 26 is formed between the nozzle and a sleeve. By this constitution, the contact pressing of the nozzle to a mold 12 and the closing of a nozzle injection orifice 10a are achieved by the relative slide retreat of the nozzle due to the action of a nozzle touch cylinder 28 and the opening of the nozzle injection orifice is achieved by the relative slide advance of the nozzle due to the action of the pressure generated in the pressure generating chamber.