Enzymes in the body vary among different species, and also vary among individuals of the same species. Thus, it has been demanded to develop a novel steroid-containing pharmaceutical preparation which can release a drug in a manner independent of the enzymes present in the body, and which is expected to have an efficacious therapeutic effect. Disclosed is a high-molecular weight conjugate of a steroid, comprising a structure in which a carboxylic acid group of a polymer having a polyethylene glycol moiety and a succinic acid monoamide moiety having two or more succinic acid monoamide units is ester-bonded to a hydroxy group in the steroid.
