A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, includes a drum unit having an electrophotographic photosensitive drum; and a developing unit rotatably connected with the drum unit at a center of rotation. The developing unit includes a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum with a developer, a developer accommodating portion accommodating the developer, and a supply opening, extending in an axial direction of the developing roller, for supplying the developer to the developing roller from the developer accommodating portion. The rotation axis is within a width of the sealing member as seen in a direction perpendicular to a surface of the sealing member.