Abstract: This invention provides as a novel drug carrier into a living body a highly water-soluble polymer that can carry and release a drug at a desired rate and a supramolecular-structured biodegradable polymeric assembly that can release the drug it carries as a function of the specific behavior of biodegradation of a diseased body. A supramolecular-structured biodegradable polymeric assembly according to the invention comprises lots of drug-binding cyclic compounds obtained by combining the drug with .alpha.-, .beta.- and .gamma.-cyclodextrins and a linear polymeric chain compound threading through the structural cavity of the cyclic compounds, said linear polymeric chain with biodegradable sites at the both terminals thereof.