An image forming apparatus is capable of performing image formation at a processing speed of not lower than 150 mm/s. An electrophotographic photoreceptor comprises a surface layer containing a siloxane-bases resin having charge-transporting properties and a crosslinked structure. A cleaning device comprises a brush member disposed such that the leading end of said brush comes in contact with said electrophotographic photoreceptor. The product (R.sub.z.times.W.sub.e) of the surface roughness (R.sub.z [.mu.m]) of said electrophotographic photoreceptor after 200,000 rotations thereof and the wear rate of said electrophotographic photoreceptor per 1,000 rotations (W.sub.e [nm]) is not greater than 20.