A rocker arm changeover device for an engine includes a major rocker arm to drive intake or exhaust valves. A driven rocker arm is arranged in line with the major rocker arm. A changeover pin is movable within a first pin hole and a second pin hole and to change between engagement and disengagement of the major and driven rocker arms. The first pin hole coaxially matches the second pin hole through rocking motions of the major and driven rocker arms. A first pin is movable within the first and second pin holes between a disengagement position at which the first pin is retracted into the first pin hole and an engagement position at which the first pin protrudes from the major rocker arm. A second pin is movable relative to and coaxially with the first pin within the first pin hole.