A water-repellent film is applied on to the surface of a welding member such as of a welding backing member disposed backside a joint defined between two mating welding bevels, a welding bevel of a base member to be welded, and a coated welding rod formed by coating a metallic core wire with a flux. The water-repellent film is formed of a hydrophobic material having a contact angle of 90.degree. or above and providing minute concavities and convexities. In a highly humid environment, during rainfall or in water, welding can be effected without weld defects such as blow holes, cracks and the like.