In an internal combustion engine with two cylinder banks, each cylinder bank having a cylinder head mounting thereon a valve operating device enabling both valve timing and valve lift characteristic to be varied, each valve operating device drives an engine valve through an eccentric cam, a substantially ring-shaped link, a rocker arm, a rod-shaped link, and a rockable cam, by rotation of a drive shaft. A control shaft varies the attitude of the rocker arm via a control cam by rotary motion thereof, in order to change a valve lift characteristic of the engine valve. As viewed in the same axial direction, a lifting direction of the rockable cam relative to a rotational direction of the drive shaft is the same in the two cylinder banks.