Rotation of intake and exhaust valves are very closely related to the long term durability of automotive engines. If the valves do not rotate even at a rated engine speed, it causes the uneven wear of the valve seat and valve head contact area, which eventually shortens the engine life. A principle of valve rotation mechanism was presumed based on some findings from experiments, and computer programs were developed to simulate the valve rotation phenomena. In this study we investigated the valve rotation mechanism by using the computer simulation models.