Provided is a method of producing an electrophotographic photosensitive member having improved sensitivity and capable of outputting an image having less image defects due to a ghost phenomenon not only under a normal-temperature, normal-humidity environment but also under a low-temperature, low-humidity environment as a particularly severe condition. The method of producing a gallium phthalocyanine crystal includes subjecting a gallium phthalocyanine and a specific amine compound, which are added to a solvent, to a milling treatment to perform crystal transformation of the gallium phthalocyanine. In addition, the gallium phthalocyanine crystal is used in the photosensitive layer of the electrophotographic photosensitive member.