A molten resin containing reinforcing fibers is injected from a gate into a cavity formed between an external piece and a center pin, and the molten resins containing the reinforcing fibers join together in the cavity. Thus, a weld line is formed in the molten resin containing the reinforcing fibers in the cavity. With this injection molding mold, moving the external piece with respect to the center pin changes an interval with the center pin. This forcibly causes the molten resin containing the reinforcing fibers in the cavity to flow and disturbs directions of the reinforcing fibers at the weld line. Consequently, the reinforcing fibers at the weld line and near the weld line in a cylindrical article tangle, improving strength at a part where the weld line is formed in the cylindrical article.