To realize a variable valve-lift system provided with a variable lift-amount as specified by design values in which variation in lift amounts among cylinders is reduced even in the low-lift region where high accuracy is needed.

The variable valve mechanism of an engine includes camshafts equipped with a three-dimensional cams, a rocker-shaft-driving means, and a valve-lift amount-changing means for changing the valve-lift amount in accordance with a displacement of the rocker shaft. The valve-lift amount-changing means is made up of a 1st rocker-arm and a 2nd rocker-arm. Out of both ends of the rocker shaft, one end closer to the side of a cam-profile formed so as to minimize the lift amount is made up to a dimension reference-face in the case of mounting the 2nd rocker-arm and a roller to the rocker shaft.