Shape-memory biodegradable and absorbable materials which make it possible to easily treat vital tissues by suture,
anastomosis,
ligation, fixation, reconstitution,
prosthesis, etc. without causing burn. These materials never induce halation in MRI or CT and never remain
in vivo. Such a shape-memory biodegradable and absorbable material is a material made of a molded article of
lactic acid-based
polymer and can be recovered to the original shape without applying any external force thereto but heating to a definite temperature or above. It is obtained by deforming a molded article (a primary molded article) made of a
lactic acid-based
polymer and having a definite shape into another molded article (a secondary molded article) having another shape at a temperature higher than the
glass transition temperature thereof but lower than the
crystallization temperature thereof (or 100.degree. C. when the molded article has no
crystallization temperature) and then fixing said molded article to the thus deformed shape by cooling it as such to a temperature lower than the
glass transition temperature. When this material is heated to the above-mentioned deformation temperature or above, it is immediately recovered to the original shape. The
lactic acid-based
polymer is hydrolyzed and absorbed
in vivo.