A process cartridge detachably attachable to an electrophotographic apparatus main body, the process cartridge comprising: an electrophotographic photosensitive member; a toner; and a developing roller, wherein a surface layer of the electrophotographic photosensitive member has a Martens hardness of 245 to 300 N/mm 2 as measured with an indentation force of 7 mN, the developing roller comprises: an electroconductive substrate (2; 45); and a single-layered surface layer (1; 44) containing a binder resin on the substrate, characterized in that when an elastic modulus of the binder resin, measured as indicated in the description, in a first region is El, the first region being a region from an outer surface of the single-layered surface layer (1; 44) to a depth of 0.1 μm, and an elastic modulus of the binder resin, measured as indicated in the description, in a second region is E2, the second region being a region from a depth of 1.0 μm to a depth of 1.1 μm from the outer surface, as measured in a cross section in a thickness direction of the single-layered surface layer (1; 44), the following formulas and are satisfied: E 1 ≥ 200 MPa 10 MPa ≤ E 2 ≤ 150 MPa the elastic modulus in the second region continuously decreases from that in the first region, the toner comprises a toner particle, and an external additive A, the external additive A is a silica particle having a major diameter of 40 to 400 nm, a coverage of the external additive A with respect to a surface of the toner particle is 3.0% or more, and wherein 3.0 < El × (H/100) × (1-S/100) < 400.0 is satisfied, when the coverage of the external additive A with respect to the surface of the toner particle, measured as indicated in the description, is H%, and a fixation rate of the external additive A obtained by SEM observation of the toner, measured as indicated in the description, is S%. an electrophotographic photosensitive member; a toner; and a developing roller, wherein a surface layer of the electrophotographic photosensitive member has a Martens hardness of 245 to 300 N/mm 2 as measured with an indentation force of 7 mN, the developing roller comprises: an electroconductive substrate (2; 45); and a single-layered surface layer (1; 44) containing a binder resin on the substrate, an electroconductive substrate (2; 45); and a single-layered surface layer (1; 44) containing a binder resin on the substrate, characterized in that when an elastic modulus of the binder resin, measured as indicated in the description, in a first region is El, the first region being a region from an outer surface of the single-layered surface layer (1; 44) to a depth of 0.1 μm, and an elastic modulus of the binder resin, measured as indicated in the description, in a second region is E2, the second region being a region from a depth of 1.0 μm to a depth of 1.1 μm from the outer surface, as measured in a cross section in a thickness direction of the single-layered surface layer (1; 44), the following formulas and are satisfied: E 1 ≥ 200 MPa 10 MPa ≤ E 2 ≤ 150 MPa the elastic modulus in the second region continuously decreases from that in the first region, the toner comprises a toner particle, and an external additive A, a toner particle, and an external additive A, the external additive A is a silica particle having a major diameter of 40 to 400 nm, a coverage of the external additive A with respect to a surface of the toner particle is 3.0% or more, and wherein 3.0 < El × (H/100) × (1-S/100) < 400.0 is satisfied, when the coverage of the external additive A with respect to the surface of the toner particle, measured as indicated in the description, is H%, and a fixation rate of the external additive A obtained by SEM observation of the toner, measured as indicated in the description, is S%.