To impart excellent weather resistance and corrosion resistasnce to a steel and to unnecessiate the maintenance therefor by coating the surface of a weather resistant and seawater resistant steel with a thermal spraying layer essentially consisting of Al at a specified coating ratio (area ratio).

On the surface of a low alloy steel base material, a thermal spraying layer contg., by weight, ≥90% Al is formed at a coating ratio (area ratio) of ≤99.5%. As the base material, a weather resistant and seawater resistant steel contg., by weight, 0.001 to 0.25% C, 0.01 to 2.0% Si, 0.01 to 10.0% Mn, 0.001 to 0.5% P and 0.20% S, furthermore contg. one or ≥ two kinds among 0.05 to 2.5% Cu, 0.05 to 10.0% Ni, 0.05 to 15.0% Cr and 0.05 to 6.0% Mo, and the balance Fe with inevitable impurities is used. It is required that the Al sprayed film is composed of porous one having through holes or is the one discretely applied with thermal spraying and in which a part of ferrite. is exposed.