The present invention addresses the problem of manufacturing first and second members with different materials when molding injection molding body one after another using first to third molds disposed at 120 degrees from each other on a turntable that performs reciprocating motion at 120 degrees and using fourth to sixth molds provided opposite to the first to third molds, respectively. According to the solution, first to third injection devices are disposed on the sides of fourth to sixth molds, respectively, the first injection device is caused to perform primary injection to mold a first member, and the second and third injection devices are caused to perform primary injection to mold a second member and secondary injection to integrate the first and second members with each other, whereby the first and second members can be manufactured with different materials one after another.