A rocker arm 1 includes an arm body 4 prepared from a single plate material by means of a press work. The arm body 4 includes a pair of parallel side walls 5 and a connecting wall 6 bridging between the opposite side walls 5 and also having a pivot support hole 7 defined at a location generally intermediate of the length of the arm body 4. A roller support pin for rotatably supporting a roller 10 for driving engagement with a cam is mounted on one ends 1a of the opposite side walls 5, while the opposite end 1b of the connecting wall 6 defines an overlapped structure 13 formed by bending an end overlap piece 12, extending integrally from a side edge of the connecting wall 6, backwardly to overlap the connecting wall 6. This overlapped structure 13 in turn defines an adjustment element 16 having a mounting hole 15 defined therein for adjustably receiving a valve driving member 14. The rocker arm 1 may be designed to be an end pivot type, in which case the adjustment element 16 is provided with a pivot member.