Valve operating apparatus for internal combustion engine

[Object] To reduce the gap between a rocker arm and a valve with a simple structure in a valve operating apparatus for use in an internal combustion engine. [Solving Means] A valve operating apparatus for use in an internal combustion engine includes an intake cam 38, an intake rocker arm 33 rotatable about a rotational shaft 35 and driven by the intake cam 38, and an intake valve 40 pushed by a pusher 70 of the intake rocker arm 33. The internal combustion engine has a cylinder assembly 12L lying horizontally. The intake rocker arm 33 has a weight 67 adjusting the center of gravity of the rocker arm 33 to position the pusher 70 above the rotational shaft 35 while the intake cam 38 is held out of abutting contact with the intake rocker arm 33.