A novel podophyllotoxin derivative, which is capable of releasing a drug without depending on biological enzymes and can be expected to have an effective therapeutic effect and is soluble in water has been demanded. A polymer having a polyethyleneglycol structural unit and two or more succinic monoamide structural units, particularly a polymer conjugate of a podophyllotoxin in which a carboxylic acid group of polyethyleneglycol/polyaspartic acid copolymer and a hydroxyl group of podophyllotoxin and linked via an ester bond is provided.
