To provide a powder supply device and a powder supply method capable of making small the difference in the powder supply density caused by the supply position by suppressing the generation of a bridge to the utmost, in supplying the powder in a cavity.

Into the inside of a powder box 16, air is introduced to raise the inside air pressure, Under this condition, a shutter 40 is opened, and the powder is discharged (fell) vigorously to fill the cavity 5. In such a way, by increasing the discharge (falling speed) of the powder to be filled, the generation of a bridge inside the cavity 5 is suppressed so that the diffence in the filling desity caused by the supply position is made small.