To supply lubricating oil to a slide part while suppressing the complication of a component structure of an intake camshaft.

An engine with a variable valve system is provided with a first intake valve 12 and second intake valve 13 in each cylinder. The intake camshaft 2 comprises the first intake camshaft 21 equipped with the first intake cam 10 for driving a first intake valve 12 and the second intake camshaft 22 equipped with a second intake cam 11 for driving a second intake valve 13, and is further provided with a cam phase variable mechanism 20 varying a rotational phase of the first intake camshaft 21 and second intake camshaft 22. The first intake cam shaft 21 is formed in a hollow shape, and the second intake camshaft 22 is inserted into the first intake camshaft 21 with a clearance 58 and concentrically arranged. The clearance 58 is used as a lubricating oil passage, and communicate with the sliding part of the first intake camshaft 21 and cam journal 23b.