Abstract: The object of the present invention is to provide an absorption enhancer capable of introducing high-molecular weight compounds into cells. The object can be solved by a composition of the present invention comprising a polymer compound having a group represented by the following general formula (1) or the following general formula (2) at a side chain, and a compound to be administered with a molecular weight of 1,000 to 1,200,000. wherein X1 is a residue of neutral amino acid or ?-aminoalkanoic acid in which an end amino group and an end carboxyl group are removed, X2 is a residue of cell-penetrating peptide in which an end amino group and an end carboxyl group are removed, X3 is a hydroxyl group, an amino group, an alkoxyl group having 1 to 4 carbon atoms or a benzyloxy group, a is an integer of 0 to 50, and * denotes a bonding site.