A molding machine, which is operable to mold plastic granules into a plastic piece, includes a machine body, a platform, a heater, and a pressing unit. The platform is installed at the machine body and defines a molding cavity to receive the plastic granules. The heater is installed at the machine body adjacent to the platform. The pressing unit is installed at the machine body and disposed above the platform. The pressing unit includes a pressure cylinder, a telescopic rod driven by the pressure cylinder to extend downward and retract upward, and a pressing plate coupled to the telescopic rod and disposed to correspond in position with the molding cavity, and driven by the pressure cylinder to move relative to the platform.