An injection molding apparatus includes a vessel, mold, pusher, and thrust providing section. The vessel stores a molding material and has a nozzle hole which is formed in the bottom portion to inject the molding material and a first seal surface formed around the nozzle hole. The mold is made up of stacked members stacked on the lower side of the vessel and is filled with the molding material injected from the vessel. The mold has a sprue communicating with the nozzle hole and a second seal surface formed around the sprue. The stacked members respectively have third seal surfaces at portions where the members are in contact with each other. The pusher pressurizes the molding material in the vessel. The thrust providing section provides a thrust to the pusher to pressurize one of the pusher and the mold through the molding material in the vessel. The thrust providing section brings the first, second, and third seal surfaces into tight contact with each other by providing a downward thrust to the pusher with respect to the mold. An injection molding method is also disclosed.