Method of forming double-bonded corrosion protection coatings on prestressing strand and prestressing strand

To improve a tensile strength without impairing flexibility and adhesion strength to concrete, and to form thick coating in a surface layer part for preventing a basis material from being exposed by a damage of the coating, a method of forming double coatings on a prestressing strand includes a primary painting process after a pre-treatment process, in which a resin coating is formed only in the surface layer, a secondary painting process in which respectively individual state resin coating is formed on outer peripheral face of each of the core wire and the surrounding wires under a loosened and separated state, thereby forming a double coating in each surrounding wire, and a finishing process of tightening and retwisting the surrounding wires about the core wire to an original state. The obtained prestressing strand has the double coating portions only in the surface layer thereof and enough flexibility and adhesion strength to concrete.