An internal combustion engine having a plurality of banks; each having a cylinder provided to said banks comprising: an intake valve provided between said cylinder and an intake manifold a camshaft opening and closing said intake valve by means of mechanical power of said internal combustion engine; and a changing unit changing, according to an operating state of said internal combustion engine a phase angle of said camshaft said phase angle corresponding to a closing timing of said intake valve said banks differing from each other in most retarded phase angle changed by said changing unit.