PURPOSE: To heat a form equally in a short time by moving the preform of compound material consisting of a reinforcing fiber dispersed in a thermoplastic resin in an axial direction so that the molding is stuck through a heating gas discharge tube, and allowing a heating as to be released from the heating gas discharge tube.

CONSTITUTION: A fiber-reinforced plastic molding which is charged individually from a charging port 1a is molded. A preform manufactured as a blank in a preceding stage is fed in an arrow A direction by the advancing motion of a plunger 2, and is sequentially stuck through a heating N2 gas discharge tube 3 starting with the one at the head by repetition of the plunger action. From the fine hole 3a of the discharge tube 3, the heated N2 gas is radially charged into the molding P, passing through the fibrous tissue voids of the preform and the preform is heated. This molding P receives a larger amount of heat at the right end, so that it is transformed from a solid phase into a molten resin blend M continuously to be discharged from a discharge port 1b.