Novel cold rolling oils for steels comprise (A) 40 to 90 wt % of a monoester of an aliphatic carboxylic acid having 12 to 22 carbon atoms and an aliphatic alcohol having 1 to 12 carbon atoms, (B) 0.5 to 10 wt % of at least one of a dimer acid and a polymerized acid of a higher aliphatic unsaturated acid having 16 to 20 carbon atoms, (C) 2 to 40 wt % of a polyester having a molecular weight of 750 to 7500 and obtained by subjecting at least one of a dimer acid and a polymerized acid of a higher aliphatic unsaturated acid having 16 to 20 carbon atoms to condensation with a polyol under heating conditions and reacting remaining carboxyl groups of hydroxyl groups of the resulting polyester with an alcohol having 1 to 22 carbon atoms or an aliphatic acid having 12 to 22 carbon atoms, or 10 to 25 wt % of fat and fatty oils, and (D) 0.1 to 10 wt % of a polymer compound having nitrogen atoms in a molecule having a molecular weight of 1,000 to 1,000,000 such as a homopolymer or copolymer of monomers of the following general formula: ##STR1## in which R.sub.1 represents H or CH.sub.3, R.sub.2 and R.sub.3 independently represent H or an alkyl group having 1 to 3 carbon atoms.The cold rolling oils for steels have good lubricity, surface cleanability with excellent heat resistance and oxidative stability.