PURPOSE: To perform uniform mixing of granular materials continuously by providing a freely tiltable mixing control plate between a plurality of juxtaposed metering hoppers and a common receiving hopper below the metering hoppers, and providing a mixing device in the mixing chamber provided continuously to the lower part of the receiving hopper.

CONSTITUTION: At the time of sealing, for example, mixture K of polished rice H and barley M into a bag B, metering of both H, M is set in a metering part S, and a mixing control plate 18 is fixed to the barley M side of a smaller mixing rate at a predetermined inclination angle α. Next, the mixing impeller 15 in a mixing chamber 14 is run; at the same time, polished rice and barly supply chutes 4, 5 are opened to allow the polished rice and the barley to fall at the predetermined rates into metering hoppers 7, 8 respectively. Further, they are dropped into the respective sections 12', 12" in the receiving hopper 12 partitioned by the mixing control plate 18. They are dropped through the respective discharge ports 13', 13" into the mixing chamber 14 at a predetermined ratio by said receiving hopper 12, and are thereby mixed uniformly. Finally, the mixture is packed in the bag B.