PURPOSE: To provide the oil cooler for marine capable of improving strength and heat exchanging rate without reducing resistance to seawater corrosion and being manufactured with an inexpensive cost by constituting the body of the cooler with a clad member of a seawater resistive alloy and other metal.

CONSTITUTION: The seawater resistive alloys (Monel alloy) 1a, 2a are arranged at an outside and other metals 1b, 2b are arranged at an inside to enclose a fin 3. The fin 3 is formed by a copper plated plate of iron or iron alloy and is enclosed by an upper plate and a bottom plate to form an oil path 4. The heat emission of oil, passing through the oil path, is effected by the fin. Both ends of the bottom plate 2 are bent so as to cover both ends of the upper plate 1 under a condition that copper brazing member is interposed between them. Both plates are heated at the temperature of about 1,100°C for thirty minutes and the exposed surfaces of stainless steel of both end surfaces of the bottom plate are covered by copper 5. The oil cooler for marine thus constituted is covered by the copper in both ends, which are readily corroded by the invasion of seawater, especially in the surface of the stainless steel, therefore, corrosion may be restricted and the strength of the cooler may be improved.