A solid lubricant-coating device is provided with a solid lubricant to be applied to the surface of a latent image-supporting member; a supply roller for scraping and supplying the solid lubricant onto the surface of the latent image-supporting member by self rotation; a pressing unit for pressing the solid lubricant onto the supply roller; a flattening unit for forming a thin film of the supplied solid lubricant on the surface of the latent image-supporting member; and a cleaning unit for removing the residual toner on the surface of the latent image-supporting member and recovering the solid lubricant thin film on the surface of the latent image-supporting member, wherein, when a thickness of the solid lubricant thin film immediately before the supply roller in the rotation direction of the latent image-supporting member is designated as thickness A (nm) and a thickness immediately after the flattening unit is designated as thickness B (nm), the thicknesses A and B satisfy the following relational formulae (1) and (2): B−A≧8 (1) and A≧4 (2).