First, a horizontal nozzle is inserted between an upper mold section and a lower mold section in a horizontally extending state. Then, liquid resin is horizontally discharged from a discharge port of the horizontal nozzle. Thus, the liquid resin is supplied into a cavity. Thereafter the upper mold section and the lower mold section are closed. Consequently, an electronic component mounted on a substrate is dipped in the liquid resin stored in the cavity. Therefore, the electronic component is resin-sealed on the substrate by compression molding.