To provide a photoreceptor using a binder resin capable of improving storage stability of a dispersion liquid, and to provide an image forming apparatus and a cartridge using the photoreceptor.

The electrophotographic photoreceptor has at least a charge generating layer and a charge transporting layer on a conductive support, and is characterized in that: the charge generating layer contains polyvinyl acetal; and when the polyvinyl acetal is subjected to proton nuclear magnetic resonance spectroscopy using dimethyl sulfoxide-d6 as a solvent, the ratio of an area (A) of a peak having the maximum at 4.28±0.02 ppm to an area (B) of a peak having the maximum at 4.38±0.02 ppm, resulting from dividing A by B (A/B), ranges from 0.8 to 1.1. The polyvinyl acetal is obtained by reacting two or more kinds of aldehydes with polyvinyl alcohol.

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