PROBLEM TO BE SOLVED: To provide a branched hetero polyethylene glycol which has two kinds of functional groups capable of reacting with bio-functional substances and has multiple occurrences of one of the functional groups.SOLUTION: The present invention provides a compound represented by the formula [1]. (X and Y each represent an atomic group containing a functional group which reacts with a functional group present in a bio-functional molecule, provided that X and Y are different from each other； s is an integer of 2 to 8； n satisfies 20&le；n&le；2000； and E is a branching linker moiety having s-valent bonding valency and having monovalent bonding valency for the functional group Y.【課題】生体機能物質と反応可能な2種の官能基を有し、かつ一方の官能基を複数持った分岐型ヘテロポリエチレングリコールの提供。【解決手段】式[１]で示される化合物。(X、Yは，生体機能性分子の官能基と反応する官能基を含む原子団、XとYは互いに異なる。sは、２～８の整数。nは、20≦n≦2000。Eは、s価の結合価数を有し、原子団Yに対して1価の結合価数を有する分岐リンカー部位。)【選択図】なし
