To provide an electrophotographic photoreceptor which has an undercoat layer and a photosensitive layer successively layered on a conductive supporting body and which suppresses increase in a residual potential and production of an image with black spots during repeated use, and to provide an image forming apparatus and a process cartridge, and a coating liquid for an undercoat layer having preferable storage stability.

The undercoat layer 2 is formed of a binder resin, titanium oxide and polyhydric alcohol, the binder resin containing at least an isocyanate compound and a resin having an active hydrogen group reactive with the isocyanate compound as composition components, and is provided on a conductive supporting body 1, and a charge generating layer 3a and a charge transport layer 3b are successively layered on the undercoat layer to constitute the electrophotographic photoreceptor. The electrophotographic photoreceptor is used to constitute the image forming apparatus and the process cartridge.