A cold-rolling lube oil for metallic materials is composed of (a) 40-90 wt. % of a monoester of a specific aliphatic carboxylic acid and a particular aliphatic alcohol, (b) 0.5-10 wt. % of at least one of dimer acids and polymer acids of certain unsaturated higher fatty acids, (c) 10-25 wt. % of a fats and fatty oils, or 5-70 wt. % of an ester obtained by reacting remaining carboxyl or hydroxyl groups of a specific polyester with a specific alcohol or fatty acid, (d) 0.3-10 wt. % of a phenol-type antioxidant, and (e) 0.3-10 wt. % of a sulfur-type antioxidant.