An ashing device that prevents the ashing rate from changing over time. The ashing device ashes organic material on a substrate including an exposed metal in a processing chamber. The ashing device includes a path, which is formed in the processing chamber and through which active species supplied to the processing chamber pass. The path is defined by a surface on which the metal scattered from the substrate by the active species is collectible, with the surface being formed so as to expose a metal that is of the same kind.