An electrophotographic photosensitive member (1) includes a conductive substrate (2) and a photosensitive layer (3). The photosensitive layer (3) is a single-layer photosensitive layer. The photosensitive layer (3) contains a charge generating material, a hole transport material, an electron transport material, a binder resin, and an additive. The additive contains a carboxylic acid anhydride. A reduction potential of the carboxylic acid anhydride is at least -1.40 V versus a reference electrode (Ag/Ag + ). The carboxylic acid anhydride is contained in an amount of at least 0.02 parts by mass and no greater than 10.00 parts by mass relative to 100 parts by mass of the binder resin.