In a positively charging single layer type electrophotographic photoreceptor having an over coat layer, an electrophotographic photoreceptor that is excellent in mechanical strength, electric characteristics, and adhesiveness, an electrophotographic photoreceptor cartridge, and an image formation device are provided. In a positively charging electrophotographic photoreceptor having a single layer type photosensitive layer and an over coat layer, the Martens hardness on the photoreceptor surface satisfies the prescribed condition, and preferably the photosensitive layer satisfies the particular relational expression of the contents and the molecular weights of the hole transporting substance and the electron transporting substance contained therein, thereby solving the problem.

The undercoat layer contains metal particles and a polyamide resin. The metal particle has a core and a coat layer covering at least a part of the core. The core contains titanium oxide. The coat layer contains at least a metal oxide different from titanium oxide. The metal oxide different from the titanium oxide is located on the outermost surface of the metal particles. The polyamide resin has an amide bond and an alkylene group. The absorption rate of the first peak derived from the amide bond to the second peak derived from the alkylene group to the first absorbance measured by infrared spectroscopy is ≥0.70.