The present invention discloses an electrophotographic photosensitive member, a process cartridge, and an image forming apparatus. The electrophotographic photosensitive member includes a conductive substrate and a monolayer type photosensitive layer. The difference [delta]Ea-Ip between the work function Ip of the conductive substrate and the electron affinity Ea of the charge-generating materialis in the range of about 0.1 to about +0.1 eV. When a gold electrode formed with a film thickness of 2 nm and an electrode area of 9.3*10 1 cm 2 is provided on the photosensitive layer, the difference [delta]Iab between the current Ia [A/cm 2] and the current Ib [A/cm 2] is in the range of about 5.5*10 8 to about 9.2*10 8 [A/cm 2 ], the currents Ia and Ib are respectively the currents per unit area when the gold electrode and the conductive substrate become positive electrodes by voltage application and when an electric field of 27 V/um was applied between the photosensitive layer and the conductive substrate in an environment of 33 DEG C and a humidity of 80%.