A powder supplying device (2) includes a case (6) in which a storage portion (6a) is formed for temporarily storing powder (10), the case (6) having an inlet (6b) formed in an upper end of the storage portion (6a), and a rectangular outlet (6c) formed in a lower end of the storage portion (6a); a rotor (7) that is arranged in the case (6) and transports the powder (10) in the storage portion (6a) to the outlet (6c) by rotating; and a mesh body (8) through which the powder (10) that has been transported to the outlet (6c) passes. The powder supplying device (2) supplies the powder (10) onto an upper surface of an electrode foil (5). The rotor (7) has a brush-like shape, with a plurality of hair members (7b) radially implanted pointing radially outward with an axial center (G) of the rotor (7) as the center.