PURPOSE: To generate swirl in intake gas by making difference between valve lifts of a plurality of valves at the time of a low load, in the valve driving device of an internal combustion engine for changing the phase and the abutting position of a cam which abuts on a rocker arm so as to change a valve timing and the valve lift.

CONSTITUTION: An auxiliary rocker arm 18 is opposed to a rocker arm 17 provided with a driving part 172 which abuts on a specified intake valve 7a2, and they are fit on each other on a free end side. When a cam shaft 28a is transferred from a high load position H to an intermediate load position M, the valve lift of the intake valve 7a2 is gradually reduced by a cam 52 and a rocker arm 17. And when the cam shaft 28a is transferred from the intermediate load position M to a low load position L, the valve lift is increased again by a cam 53 and the auxiliary rocker arm. It is thus possible to generate valve lift difference between the intake valve 7a2 the other intake valve so as to generate swirl in intake gas.