Electrophotographic photoreceptor and image formation device provided with the same

An electrophotographic photoreceptor comprising a conductive support and a photosensitive layer obtained by laminating at least a charge generation layer and a charge transport layer containing a charge transport material in this order on the conductive support, the photosensitive layer being provided with a surface protective layer on the surface thereof, wherein the protective layer contains at least filler particles which exhibit a dispersed state defined by Rf given by the following equations (1) and (2):

• Rf=(df×b3)/(dm×a3) (1)
• 1.0×10−3≦Rf≦2.5×10−2 (2)
• wherein a is an average distance (nm) between fillers, b is an average particle diameter (nm) of fillers, df is a density (g/cm3) of filler particles and dm is an average density (g/cm3) of a solid in the surface protective layer, and a diamine compound represented by the following formula (I):
• wherein Ar1, Ar2, Ar3 and Ar4, which may be the same or different, each represent an aryl group, cycloalkyl group or monovalent heterocyclic residue which may have a substituent;
• Ar5 represents an arylene group or a divalent heterocyclic residue;
• and Y1, Y2, Y3, Y4, Y5 and Y6, which may be the same or different, each represent a chain alkylene group which may have a substituent.