PURPOSE: To improve feed (discharge) efficiency and controllability by providing piston cylinder type chambers at opposite positions in the radial direction of a rotor movable around a horizontal axis, and allowing pistons within the respective chambers to be integrally interlocked.

CONSTITUTION: A rotor 8 rotatably supported by shaft parts 15A, 15B thereof is housed in a cylindrical casing 1 including an introduction inlet 5 formed at its top part and a discharge outlet 6 at its bottom part, and a pair of cylinders 9, 10 are formed at opposite positions in the radial direction of the rotor 8. These cylinder parts 9, 10 are communicated with each other through a central opening part, and integrally connected pistons 11, 12 are fitted in the respective cylinders 9, 10. Both of the pistons 11, 12 are made movable due to force of gravity and self weight of a supplied material. Top surfaces of the respective pistons 11, 12 are circular arc-shaped corresponding to the circular arc of the outer periphery of the rotor 8, while an anti-adhesion agent 14 for preventing adhesion of powdered materials, etc., is stuck thereon.