An electrophotographic photoreceptor includes an outermost layer formed of a polymerized cured product of a composition containing a polymerizable monomer and metal oxide particles surface-treated with a surface treatment agent having a silicone chain, wherein a ratio (r/r′) between a number average primary particle diameter (r) of metal oxide particles which are untreated base particles of the metal oxide particles surface-treated with the surface treatment agent having a silicone chain and a sphere equivalent particle diameter (r′) of the untreated base particles calculated from a specific surface area measured by a nitrogen adsorption method is 1.5 or more and 6.0 or less, and a surface treatment amount with the surface treatment agent having a silicone chain per surface area of the untreated base particles is 0.0005 g/m2 or more and 0.0015 g/m2 or less.