(EN) This injection device injects and fills the inside of a mold with a molding material and increases the pressure. The injection apparatus is provided with a unit for a low speed step a unit for a high speed step a unit for a pressure increasing step and an injection plunger. A rod of a first unit which is any one of the three units is mechanically coupled to the injection plunger. A rod of a second unit which is one of the two units other than the first unit is mechanically coupled to the first unit. A rod of a third unit which is the unit other than the first and second units is mechanically coupled to the second unit.