A method for producing a polyhydroxyalkanoate using a microorganism capable of substantially reducing unintended monomer units and obtaining the polyhydroxyalkanoate in a high yield. A microorganism capable of synthesizing a novel polyhydroxyalkanoate having 3-hydroxy-substituted benzoylalkanoic acid as a monomer unit, using a substituted benzoylalkanoic acid as a material, is cultured in a medium containing a substituted benzoylalkanoic acid. Then, the polyhydroxyalkanoate produced in the cultured bacteria is extracted and recovered.