A rocker arm, which opens and closes a valve when tilted by a cam and is provided on a cylinder head, has a body made of sheet metal. The body is constituted in such a manner that one metal plate blank is bent into a substantially U shape so that a pair of opposed side walls and connecting walls for connecting the side walls are provided. A convex valve fitting section is provided on the connecting walls of the body by press working including a non-uniform cross section process producing plastic flow of material.