A development roller of an electric-photographic machine is manufactured by a method of mixing a base material of either NBR rubber or HYDRIN rubber, an electric conductive high-molecule-weight material to adjust an electric resistivity of the development roller, and peroxide as a cross-link agent cross-linking the base material and the electric conductive high-molecule-weight material in a three-dimensional structure, forming the development roller from a mixture of the base material, the electric conductive high-molecule-weight material, and peroxide, and irradiating the development roller with ultraviolet light to adjust a friction coefficient of a surface of the development roller. Accordingly, the development roller has characteristics of a low electric resistivity even with a single layer structure.