To obtain the subject composition capable of exhibiting improved heat stability and oxidation stability by adding an adding agent obtained by combining a lubricant composition with a specific antioxidant.

This lubricant composition has improved heat stability and oxidation stability by combining a lubricant composition comprising (A) a wear resistant component for an oil pressure (preferably zinc dialkyldiphosphate in a grade for an oil pressure) and (B) a base oil with (C) an adding agent comprising (i) an amine antioxidant (e.g. diphenylamine, a phenyl-α- naphthylamine or the like) and (ii) at least one kind of additional antioxidant selected from a no ash dithiocarbamate [preferably methylene-bis(di- butyldithiocarbamate)], an olefin sulfide (preferably a mixture of an isomerized 16-18C α-olefin) and a phenolic antioxidant (preferably 2,6-di-t-butylphenol).