DRUGS RETAINED IN TARGET TISSUE OVER LONG TIME

Provided are a polyethylene glycol-bound ligand in which a polyethylene glycol chain is bound to a ligand having a binding affinity to a specific receptor or a protein such as an antigen or the like present on a cell membrane of a target tissue and having an ability to avoid internalization (incorporation) into cells and a medicament in which a drug such as a physiologically active protein or the like is bound to the polyethylene glycol chain thereof. A novel ligand which is accumulated at a high concentration around a target tissue and has a high retention property in blood and an excellent medicament in which a drug effective for the target tissue, such as a physiologically active protein or the like, is introduced therein can be provided.