PURPOSE:To enhance productivity by actuating a knead extruding section continuously to send kneaded material to an injection molding section and shortening the time required by the whole of molding process. CONSTITUTION:Powder synthetic rubber 5, while being kneaded with a kneading screw 4, is sent from a knead extruding section 1 to an injection molding section 2 through an interconnecting section 7 gradually. After kneading is completed, the kneaded material sent by a plasticizing screw 9 in carried to a cylinder 13, and the quantity of injection molding is measured by a plunger section 18. Then, the kneaded material 17 is injected into a mold 12 through a rotary valve 11 by a plunger 14. At that time, a kneading screw 4 rotates, kneads and extrudes powder synthetic rubber 5 in an hopper 6 continuously without stopping rotation to carry out a continuous production.