A surface-treated metal sheet for adhesion to polyolefin includes a metal sheet, and a resin layer provided on at least one surface of the metal sheet. The resin layer contains an acid- modified polyolefin, the acid-modified polyolefin contains a first acid-modified polyolefin having an acid value of 5 mgKOH/g or less, particularly 4 to 5 mgKOH/g, and a second acid- modified polyolefin having an acid value of 20 mgKOH/g or more and a melting point of higher than 90° C., and a difference between a melting point of the first acid-modified polyolefin and the melting point of the second acid-modified polyolefin is 0° C. or more and less than 40° C. The resin layer has a surface roughness of 12 μm or less in terms of arithmetic average roughness Ra.