A method for preventing adhesion of aluminum onto the surface of a metallic product, which can be performed by a simple treatment, at low cost and within a short time. Tin granules having an average particle diameter of 10 to 100 μm and each having an oxide film formed thereon are sprayed onto the surface of a metallic product under a spraying pressure of 0.5 MPa or more or at a spraying velocity of 200 m/sec or more to form a tin oxide coating film at a thickness of 1 μm or less on a portion of the surface of the metallic product, wherein the portion of the surface of the metallic product is a portion at which the metallic product is in contact with aluminum or an aluminum alloy. By forming the tin oxide coating film, it becomes possible to prevent the adhesion of aluminum onto a metallic product.