Abstract: An injection molding machine for molding hollow plastic products which includes a pair of molds wherein one of the molds is supported rotatably about the center axis thereof a frame of the machine and each of the molds has at least one set having one male die and two female dies arranged on each product plane at an equal distance from an equal angular pitch about the center axis thereof. The rotatable mold is rotated reciprocally between first and second angular positions at each of which a primary molding of a pair of half products and a secondary molding of a complete product are performed simultaneously.