COATED STEEL SHEET AND SHEATH MEMBER

PROBLEM TO BE SOLVED: To improve the corrosion resistance in an outdoor exposure environment of a cut end face or a bending part in a coated steel sheet in which a molten Zn-Al plated steel sheet or a molten Al plated steel sheet is made an original sheet. SOLUTION: In the coated steel sheet having a chemical treatment membrane 3, an under coating film 4, and a finishing coating film 5 on the plated layer of a plated steel sheet in which an Al-containing plated layer 2 is formed by using a melt plating bath which contains 5-95 mass% of Al and at least one of 95 mass% or below of Zn, 10 mass% of Mg or below, and 12 mass% of Si or below as residual elements and in which the total content of elements excluding Al, Zn, Mg, and Si is 3 mass% or below (including 0 mass%), the undercoating film contains 10-35 mass% of at least one of manganese phosphate and manganese phosphite as pigment, so that the coated steel sheet is characterized. The average thickness (after drying, per one side of the steel sheet) of the undercoating film is preferably 2-25 μm. COPYRIGHT: (C)2010,JPO&INPIT