PURPOSE: To meter with good stability and accuracy and drop (feed) a molding material in plastic molding quantitatively at low cost by a simple mechanism.

CONSTITUTION: A tube 2 is provided on the lower section of an introduction hopper 1 for introducing a molding material 14. The tube 2 is set on the upper section of a metering chamber 3 in a manner of positioning an outlet of the tube 2 on the right side of the center of a rotor 5 installed in the metering chamber 3. A discharge section 16 of the molding material 14 is formed below the rotor 5 on the lower section of the metering chamber 3. In the metering chamber 3, a molding material storing plate 6 is set on an inner wall 4 on the molding material feeding side so that a clearance 1 is formed between the plate and the rotor 5. A resin thickness adjusting plate 7 is installed on a center line in the up and down direction of the rotor 5 on the inner wall 4 of the metering chamber above the rotor 5 in a manner of forming a clearance (d) between the plate and the rotor 5.