A skin information processing method for a skin information processing device that includes a storage portion includes acquiring an image, determining a plurality of base points from the acquired image, and acquiring position information, for the each of the plurality of base points, corresponding to a position of the base point on the acquired image. Each of the plurality of base points representing a sweat pore on a ridge of skin. The skin information processing method includes extracting a plurality of base points disposed on a same continuous ridge, generating ridge information including, for each of a plurality of extracted base points, the position information and an arrangement order on the ridge, and causing the storage portion to store the generated ridge information, as information to be used in skin authentication.