Process cartridge and electrophotographic apparatus

A process cartridge comprising:

• an electrophotographic photosensitive member;
• and
• a contact developing device including toner and a developing roller and configured to bring the developing roller carrying the toner into contact with the electrophotographic photosensitive member to develop an electrostatic latent image formed on a surface of the electrophotographic photosensitive member,
• the process cartridge collectively supporting the electrophotographic photosensitive member and the contact developing device, and being attachable to and detachable from a body of an electrophotographic apparatus,
• wherein the electrophotographic photosensitive member includes a surface layer containing a binder resin and an electron transport agent,
• wherein the surface layer contains a polyester resin as the binder resin,
• wherein the polyester resin includes a structural unit represented by formula (P-1) and a structural unit represented by formula (P-2), and
• wherein the developing roller includes a surface layer containing a compound represented by formula (1):
• in the formula (1), R1 to R4 represent a hydrocarbon group having 1 or more and 18 or less carbon atoms and at least one of R1 to R4 represents a hydrocarbon group having 4 or more and 18 or less carbon atoms, and X− represents an anion.