Injection molding method

Method of injection molding using a mold (20) injection mold (20) injection a gate (28), a cavity (26) connected with the gate (28) and a channel (24d, 24f, 24g) comprising flow with an opening that opens onto a rear surface of a molded product, the method comprising: an injection step for injecting molten resin from the molten gate (28) into the cavity (26) resin; a step of applying pressure to apply pressure from the gate (28) against the injected resin within the cavity (26) after the step of injecting molten resin; and a step of injection fluid for injecting a fluid toward the back surface of the molded product through the channel (24d, 24f, 24g) flow, wherein the step of applying pressure and injection stage fluid running simultaneously, the pressure applied in the step of applying pressure is lower than injection pressure applied in the step of injecting molten resin, the fluid pressure applied in step injection fluid is less than the pressure applied in step pressure application, the pressure applied in the step of applying pressure is pressure that would not be sufficient to prevent a design surface of the molded product from separating from a surface of the cavity unless the injection stage fluid run simultaneously, characterized in that the fluid pressure applied in step injection fluid is pressure would not be sufficient to prevent the design surface of the molded product separates from the cavity surface unless the step of applying pressure running simultaneously.