An elastic deformation rate of a photoconductor, an additive amount of inorganic fine particles, and a rotary member are set to satisfy a relation of 0.6≤(D/(A×B/C))/(1+E/20)≤0.82, where A is a thickness of fibers of a brush, B is a bristle density of the fibers of the brush, C is a length of the fibers of the brush, D is an elastic deformation rate obtained from a hardness test conducted using a Vickers diamond pyramid indenter at a temperature of 23° C. and a humidity of 50%, and E is the additive amount of the inorganic fine particles relative to 100 parts by mass of toner particles.