A coated and plated steel sheet or coated and plated steel strip including: a steel sheet or a steel strip; a plating layer provided on one surface or both surfaces of the steel sheet or steel strip and containing zinc; a chemical conversion coating provided on the plating layer provided on one surface of the steel sheet or steel strip or provided on at least one of the plating layers provided on both surfaces of the steel sheet or steel strip; and a single-layer or multilayer coating film provided on the chemical conversion coating, in which the single-layer coating film in contact with the chemical conversion coating or the coating film, of the multilayer coating film, which is in contact with the chemical conversion coating, contains a cerium compound capable of being dissolved in an amount of 0.10 g or more with respect to 100 g of water at room temperature at a concentration of from 0.01 to 10.0% by mass, with respect to a solid content of the single-layer coating film in contact with the chemical conversion coating or the coating film, of the multilayer coating film, which is in contact with the chemical conversion coating.