An engine camshaft has a lubricating oil passage formed along the longitudinal axis of the same, a cam communicating oil hole is radially formed from the lubricating oil passage to an outer peripheral surface of the camshaft at the same axial position as an engine valve. Cam lubrication holes are radially formed from the inside to cam surfaces of cam lobes formed around a cam carrier fitted around the camshaft. One of the cam lubrication holes of the cam lobes shifted to a position for operating the valve communicates with the cam communicating oil hole of the camshaft to supply lubricant oil.