PURPOSE: To stabilize the amount of flow out of powder, by keeping the amount of gas for aerating the powder in a powder supply tank at a constant amount more than the minimum amount required for aeration when the amount of powder supply is decreased.

CONSTITUTION: A flow rate regulating valve 10 is opened to supply gas into an aerating device 3, and a pressure is applied in a dispenser tank 1. When the pressure reaches a specified pressure P1, the gas supply is stopped. Then carrier gas is flowed in a powder carrying pipe 5, a powder flow out rate control valve 4 is opened, and the pressure in the pipe 5 is increased until it reaches a specified pressure P2. Then the flow rate regulating valve 10 is opened, and gas is supplied to the aerating device 3 to perform aeration, and the powder is kept in the fluid state. At this time, when the amount of flow out of the powder is reduced and the amount of gas supply is decreased, the regulating valve 10 is controlled by a control device 15, and the amount of gas supply is kept at the amount more than the minimum amount. At the same time, a control valve 13 is opened, and the gas in the tank 1 is flowed to the carrying pipe 5 so that the pressure difference P1-P2 is kept at the specified pressure.