A silicon purification method includes a solidification purification step in which metal impurities are removed by irradiating a base material made of metallic silicon with an electron beam. The solidification purification step sequentially includes: preparing the base material to be purified at one time, loading a part of the base material into a water-cooled crucible, irradiating, with the electron beam, the entire area of the part of the loaded base material that is disposed under a high vacuum atmosphere, and thereby fully melting the part of the base material; gradually solidifying the molten part of the base material from a molten metal bottom thereof toward a molten metal surface thereof by gradually weakening an output of the electron beam so that the solidification proceeds until the solidifying portion occupies a first predetermined ratio of the total of the base material; further loading the remnant of the base material into the water-cooled crucible, and fully melting the remnant of the base material by irradiating the entire area of the remnant of the base material with the electron beam; gradually solidifying the molten metal portion from a bottom thereof toward a molten metal surface thereof by gradually weakening an output of the electron beam so that the solidification proceeds until the solidifying portion occupies a second predetermined ratio of the total of the molten metal portion; and removing an unsolidified molten metal portion.