To provide a powder and grain fixed volume supply device and a powder and grain fixed volume supply method superior in fixed volume supply performance, even when a flow passage system of powder and grain is put under atmospheric pressure or under pressurization.

A filling chamber 9 composed of a space part is formed on the tip side of a carrying means 2 connected to a storage tank 1 storing the powder and grain and carrying the powder and grain in the storage tank 1 toward a supply port 8 of the device of the next process. A regulating plate 10 forming an opening 11 passing the powder and grain in a plate, is arranged between this filling chamber 9 and the supply port 8 of the device of the next process. Deaeration is performed by forcibly enhancing bulk density of the powder and grain in the filling chamber 9 by the action of the regulating plate 10, and the fixed volume can be supplied by discharging the deaerated powder and grain to the supply port 8 while melting from the opening 11 of the regulating plate 10.