A drive cam opens or closes an intake valve via a variable mechanism, a split-type rocking cam arm, and a valve actuating mechanism. The variable mechanism varies a position of an intermediate roller corresponding to a rotating angle of a control shaft, thereby variably setting a lift amount of the intake valve. The split-type rocking cam arm includes an input arm and an output arm, and a connection selection mechanism is disposed between the arms. When the arms are connected together, the intake valve performs an ordinary open/close operation. When the arms are disconnected, an input of the drive cam is absorbed by a relative rocking motion between the arms, so that the intake valve is retained in a pause state.