This invention relates to a method of producing polyesters resulting from homopolymerization or copolymerization of a 3-hydroxyalkanoic acid(s) and having biodegradability and good physical properties using yeasts as hosts. By constructing at least one enzyme gene involved in polyester synthesis by adding a DNA coding a peroxisome-targeting signal, introducing an enzyme gene expression cassette containing that gene into yeast, and cultivating the thus-obtained transformant, it becomes possible to cause accumulation of a polyester resulting from homopolymerization or copolymerization of a 3-hydroxyalkanoic acid(s) in yeast cells and recover the polyester from the culture.