To provide a polymer or copolymer containing a piperidyl group, which has a high NO content and is useful as a stabilizer for organic materials, a material for battery electrodes and the like.

The polymer or copolymer containing a piperidyl group which contains the constituent unit represented by general formula (3) or (4) is obtained by polymerization reaction using a compound containing a piperidyl group which is represented by general formula (1) or (2).