PURPOSE:To perform a satisfactory development by making plural coloring particles adhere onto an electrostatic latent image in a constant ratio, and also to prevent abrasion of a scraping member, by using a developing sleeve obtained by performing a coarse surface treatment of 1/5-1/2 of particle size of a developer to its surface. CONSTITUTION:A control member 13 for controlling the quantity of a developer carried by a sleeve 5, and a scraping member 14 for removing it from the surface of the sleeve 5 are placed near the outlet of a developer vessel 4, and also on the surface of the sleeve 5, a lot of groove 15 are formed in its axial direction. This groove 15 is formed within the range of 1/5-1/2 of the diameter of a coloring particle so as to have such depth as one coloring particle being a developer does not enter into this groove entirely, therefore, abrasion of the scraping member 14 is reduced, also developers of 2 kinds or more can be mixed sufficiently, and the development is performed satisfactorily.