A novel polyhydroxyalkanoate having a monomer unit represented by the formula (1), the unit having a carboxyl group substituting a ring structure at the end of side chain, obtainable by oxydizing vinyl or methyl group substituting a ring structure at the end of the side chain. The polyhydroxyalkanoate has high thermal stability, charge stablity, a high charge amount, improved dispersibility and biodegradability together, and therefore, suitable for resin moldings, and binders and charge controlling agents for toners used in the electrophotographic process. ##STR00001##