An electrophotographic photoreceptor comprising a conductive substrate, and at least one layer, which contains a polymeric compound having a repeating unit selected from repeating units represented by the following general formulas (I) to (III), provided on the conductive substrate, as well as an electrophotographic process cartridge and an image forming apparatus using the electrophotographic photoreceptor. ##STR00001## In general formulas (I) to (III), R.sub.1a and R.sub.1b each independently represent an alkylene group, X represents an arylene group or an alkylene group, Y represents a divalent aromatic group, and n represents a repeating unit number.