A polyhydroxyalkanoate is disclosed which has in the molecule a unit represented by Chemical Formula (1). ##STR00001## wherein R is arbitrarily selected from a hydrogen atom, a halogen atom, CN, NO.sub.2, COOR', SO.sub.2R'', CH.sub.3, C.sub.2H.sub.5, C.sub.3H.sub.7, C(CH.sub.3).sub.2H and C(CH.sub.3).sub.3; where R' is H, Na, K, CH.sub.3 or C.sub.2H.sub.5, and R'' is OH, ONa, OK, a halogen atom, OCH.sub.3 or OC.sub.2H.sub.5; and x is an integer arbitrarily selected from 1 to 8; with the proviso that a polyhydroxyalkanoate is excluded which has a hydrogen atom as R and x in all the units is 2 or 4. Also disclosed is a process for producing the polyhydroxyalkanoate by the use of a microorganism having the ability to produce the polyhydroxyalkanoate and accumulate it in the bacterial body.