A fastening friction plate is wedged between the fastening surfaces of two fastening members in order to increase the fastening force between them. The fastening friction plate has a friction plate main body of a fixed thickness, and engaging protuberances having an approximately truncated cone shape formed on the both surfaces of the friction plate main body at a fixed pitch. The friction plate main body and the engaging protuberances are integrally formed by photo-etching into the both surfaces of a steel plate material having a fixed thickness. The hardness of the fastening friction plate is equal to or greater than that of the fastening surfaces of the fastening members.
