The present invention provides an electrophotographic photosensitive member which can output images with reduced image defects due to ghosting not only under a normal temperature and normal humidity environment but also even under a low temperature and low humidity environment as especially severe conditions, and a manufacturing method thereof; and a process cartridge and an electrophotographic apparatus each having the electrophotographic photosensitive member. Accordingly, the electrophotographic photosensitive member of the present invention having a support and a photosensitive layer on the support includes the photosensitive layer which contains a solid solution of hydroxygallium phthalocyanine and a compound represented by the following Formula (1) or Formula (1)′, the solid solution having peaks at Bragg angles 2θ of 7.4°±0.3° and 28.3°±0.3° in CuKα characteristic X-ray diffraction.