PURPOSE: To improve mass productivity by synchronizing the displacement of an injection cylinder for ejecting a biscuit and the opening displacement of a movable mold so that the advance speed of a plunger tip is made coincident with the retreat speed of the mold.

CONSTITUTION: A mold opening displacement detector 41 is provided to a movable platen 17 and an injection displacement detector 42 is provided to an injection plunger 24 to control an injection speed control valve 50. The advance distance of the plunger tip 22 detected by the detector 42 is fed back and is inputted to a differential amplifier which controls the valve 50 by the difference between the output of the detector 41 and the output of the detector 42. The displacement of the plunger trip 22 and the displacement of the movable mold 13 are synchronized by such method. The crushing of the biscuit in the mold opening stage is thus obviated and since chill time is shortened, the mass productivity of the product is improved.