PURPOSE: To obtain a molded form, provided with no unnecessary navel and prominent in surface luster, by a method wherein hot air is injection into a mold through a casting port, thereafter, resin is injected into the mold through an injection nozzle and, subsequently, the casting port is plugged by a plug, forced into the injection nozzle, and molds are clamped to mold the resin.

CONSTITUTION: A movable attaching plate 11 is elevated by an auxiliary mold clamping cylinder 12 to made a bottom force 8b with a top force 8a. Hot air, injected through a hot air injection nozzle 17, flows into the mold 8 through a casting port 9 to heat molding surface. On the other hand, resin, supplied from a supplying mechanism 2 to a plasticating mechanism 1 and transported to an injection mechanism 3, is reserved in an injection cylinder 6 and is heated by a hot air injection nozzle 17, thereafter, a slide plate 16 is moved quickly and an opening 19 is faced to the casting port 9. The resin in the injection cylinder 6 is injected from an injection nozzle 7 into the mold 8 through the casting port 9. After the injection, a plug 18 is pushed into the injection nozzle 7 as the cylinder 6 is descended and mold clamping by a main mold clamping cylinder 13 is effected in a condition that the casting port 9 is blocked. The mold 8 is cooled to cool and cure the resin.