Electrophotographic Photoreceptor, Electrophotographic Photoreceptor Cartridge, and Image Formation Device

A positively charging electrophotographic photoreceptor comprising a conductive support having thereon at least a photosensitive layer and an over coat layer,

• wherein the photosensitive layer is a single layer containing at least a binder resin, a charge generating substance, a hole transporting substance, and an electron transporting substance,
• the photosensitive layer satisfies the following expression (1) and the following expression (2),
• the over coat layer has a structure formed through polymerization of a compound having a chain polymerizable functional group, the photoreceptor having a surface having a Martens hardness of 350 N/mm2 or more:
• 0.9≤(B/b)/(A/a)≤4.0 (1)
• 0.15≤(A/a)+(B/b) (2)
• wherein in the expression (1) and the expression (2),
• A represents a content (part by mass) of the hole transporting substance per a content of 100 of the binder resin;
• a represents a molecular weight of the hole transporting substance;
• B represents a content (part by mass) of the electron transporting substance per a content of 100 of the binder resin;
• and
• b represents a molecular weight of the electron transporting substance.