A cast cylinder head 1 of an internal combustion engine to be mounted on a vehicle has an intake-side side wall 2i, an exhaust-side side wall 2e, and opposite end walls 3r and 3f. The walls 2i, 2e, 3r and 3f define a water jacket 8. A first cooling water exit part 11 and a second cooling water exit part 21 both having a solid structure are formed by casting integrally with one of the intake-side side wall 2i and the exhaust-side side wall 2e and with one of the end walls 3r and 3f, respectively. Cooling water exit openings 15,16 or 25,26 opening into the water jacket 8 are drilled selectively in either of the first cooling water exit part 11 and the second cooling water exit part 21 depending on the engine mounting position on the vehicle. Thus the same cylinder head can be used independently of the mounting orientation of the engine on the vehicle.