A vehicle engine includes: a cylinder head; a cam housing fixed to a top of the cylinder head; a cam cap fixed to a top of the cam housing; a camshaft that is rotatably supported between the cam housing and the cam cap; a cam provided around the camshaft; a rocker arm that is pushed by the cam; a supporting member that supports one end of the rocker arm from below; a cylindrical bore portion for mounting the supporting member; and a base portion for supporting a bottom surface of the supporting member. The bore portion is provided integrally with the cam housing. The base portion is provided integrally with the cylinder head.