An internal combustion engine is equipped with a variable valve control system which is operable to selectively actuate an engine valve using one of two cams of a camshaft, by sliding a rocker arm in the axial direction of a rocker-arm shaft. The system is capable of restricting the axial-direction movement of the rocker arm within a predetermined range, using a simple structure without unduly increasing the number of component parts. Position-restriction portions are formed in a rocker arm, and abut on a trigger arm to restrict sliding movement of the rocker arm within a predetermined amount, when the trigger arm is disengaged from the rocker arm.