Electrophotographic photoreceptor and image forming apparatus including the same

An electrophotographic photoreceptor, comprising:

• a cylindrical base;
• and
• a photosensitive layer disposed on the cylindrical base, wherein the photosensitive layer comprises a photoconductive layer disposed on the cylindrical base, a charge injection blocking layer disposed on the photoconductive layer, and a surface layer disposed on the charge injection blocking layer,
• the charge injection blocking layer contains at least one of nitrogen and oxygen, carbon, and a group 13 element,
• a content of the at least one of nitrogen and oxygen contained in the charge injection blocking layer is lower on a side of the surface layer than on a side of the photosensitive layer, and
• a content of carbon contained in the charge injection blocking layer is gradually increased from the side of the photosensitive layer toward the side of the surface layer.