A detergent composition for metal according to the present invention contains a specific non-ionic surfactant, a specific nitrogen-containing organic compound, a specific carboxylic acid or salt thereof, and a specific alkanol amine, and has a pH of at least 9 that is measured at 25° C. when the detergent composition is diluted to 1% by mass of an aqueous solution. According to the present invention, the detergent composition for metal having excellent corrosion inhibition properties, excellent effluent treatment properties, excellent foaming suppressing properties and excellent liquid stability in addition to high detergent properties for metal, can be provided.