To lower impact noise at the time of charging solid materials into a hopper, to improve a working environment and to lessen the nuisance to neighborhood by composing the hopper of a hollow structure and packing a soundproof material into the hollow parts.

The movable hopper 19 is constituted by a double structure formed with the hollow parts between an inner plate material 20 and outer plate material 21 made of steel plates. The stationary hopper 18 is also composed of the hollow structure hermetically closed by the inner plate material 22 and the outer plate material 23 in common use as the guide surface of the movable hopper 19 and a bottom pleat 24. The soundproof material consisting of liquid 26 is packed into these hollow parts. The vibration generated by collision of the charged material against the inner plate materials 20, 22 is damped and attenuated by the liquid 26. While the generated vibration passes the liquid 36, the vibration is partly absorbed and propagates to the outer plate materials 21, 23 and propagates to the outer space from the outer plate materials 21, 23. The level thereof is thus lowered.