roxyl group, an alkyl group, an alkenyl group, a phenyl group or an allyl group; A is a hydrogen atom and B is hydroxyl group, or A is a hydroxyl group and B is a hydrogen atom; and m and n are integers of 0 or more which meet the requirement of m+n>1, and the cyano-containing carboxylic acid epoxy adduct can be obtained by addition reaction of a cyano-containing carboxylic acid and an epoxy resin