To effectively inhibit corrosion of a copper member such as a copper tube contacting a water system, e.g. a cooling water system, by using a small amount of chemical.

A method for inhibiting corrosion of the copper member comprises adding a compound represented by formula (1) (wherein R is alkyl group or alkenyl group; and X, Y and Z are each independently hydrogen atom, alkyl group, benzyl group, hydroxyalkyl group or carboxyalkyl group, provided that the hydroxyalkyl group or the carboxyalkyl group may form a salt) and an azole corrosion inhibitor for copper to the water system contacting the copper member.