The present invention provides a variable valve operating mechanism which includes two valve operating members for opening and closing two valves individually, a drive cam provided on a single camshaft, two swing arms for transmitting a power of the drive cam to the valve operating members individually by swinging about a different axis to the camshaft, and a variable device for modifying a displacement of the swing arm per rotation of the drive cam in accordance with an operating condition of an internal combustion engine. The variable device includes a single control shaft, an actuator for driving the control shaft, and a cam device that operates in conjunction with the control shaft to dissimilate the displacement of the two swing arms.