This re-polymerizable oligomer mixt

This re-polymerizable oligomer mixture is easily collected without any especially complicated purifying step. Furthermore, the hydrolase used to conduct the depolymerization or the polymerization can be collected and repeatedly used. The invention has an advantageous point that a decrease in the activity of the enzyme is not substantially caused at this time. In the case that polylactic acid is a copolymer, a re-polymerizable oligomer mixture obtained by depolymerizing the polylactic acid copolymer is re-polymerized, thereby making it possible to regenerate a polymer having the same composition as the original polylactic acid copolymer.