Image forming apparatus and process cartridge

A process cartridge mountable to and demountable from a main assembly of an image forming apparatus that is configured to form a developer image by supplying a developer to a surface of a rotatable image bearing member and form an image on a recording material by transferring the developer image onto the recording material, the process cartridge comprising:

• the rotatable image bearing member;
• a charging roller having a surface that contacts a surface of the image bearing member, and that is configured to be rotated in contact with the rotating image bearing member and to charge the surface of the image bearing member;
• a cleaning roller having an elastic foam layer that contacts the surface of the charging roller and that is configured to be rotated in contact with the rotating charging roller and to clean the surface of the charging roller;
• and
• a developing member that is configured to supply a developer to the surface of the image bearing member and to form a developer image thereon, wherein
• E′C>E′CC when E′C is a storage elastic modulus measured within a depth of 10 μm from the surface of the charging roller in a measuring environment of 23° C., 50% RH and a measuring frequency of 10 Hz and E′CC is a storage elastic modulus of the elastic foam layer of the cleaning roller measured in the measuring environment at the measuring frequency, and
• a Martens hardness of the surface of the charging roller is 15 to 40 N/mm2 when it reaches a pushing depth of 0.1 μm.