A 55%Al-43%Zn-2%Si ternary alloy hot-dipped cold rolled steel sheet. It has the durability of 3-4 times as good as galvanized steel sheets and high corrosion resistance by the solid oxide coating of aluminum and sacrificed protection of zinc. The exterior is in light gray color with distinct fine spangles on the surface. It is applied to interior and exterior building materials with good painting adhesion.