A method and apparatus for generating a proxy signature on a right object, and a method and apparatus for issuing a proxy signature certificate. The right object proxy signature method includes receiving a proxy signature certificate in which authority for right object conversion is specified, from a right issuer; receiving a right object from a first apparatus; signing the right object; and transmitting the signed right object and the proxy signature certificate to a second apparatus. Accordingly, by allowing a right object to be signed by a third right object proxy signature apparatus, not by a right issuer, users can freely share their own content between a variety of apparatuses, and the right issuer can reduce the load associated with the conversion and signature of right objects.