This injection apparatus, which injects a molding material into a mold by operating an injection cylinder, and fills the mold with the molding material, is provided with a plurality of actuating mechanisms that are connected to the injection cylinder. Each actuating mechanism comprises an actuating cylinder that supplies an incompressible fluid to the injection cylinder, and a drive part that drives a piston of the actuating cylinder. In a low-speed step and a high-speed step for injecting the molding material, the piston of each actuating cylinder is driven forward, and hydraulic oil is supplied to the injection cylinder. In a pressure-increasing step, the pistons of the actuating cylinders are driven forward, and hydraulic oil is supplied to the injection cylinder. Because the injection apparatus is provided with a plurality of actuating mechanisms, the speed and pressure of the injection cylinder can be increased without requiring high performance from the drive parts.