Poly(L-lactic acid) (PLA) and their copolymers have a great potential for biodegradable medical materials. However limitation of their use still exists because of their crystallinity, hydrophobicity, luck of functionality, and so on. For further improvement of their properties and functionalities, various lactic acid copolymers having reactivity and amphiphilic structures were designed. In this paper, the author introduces the synthetic methods and properties of the novel lactic acid copolymers, poly(depsipeptide-random-LA), poly(depsipeptide-block-LA) and PLA-grafted polysaccharides.