A modified bio-related substance, wherein at least one poly(alkylene glycol)oxy group represented by the following formula (1) is combined in a molecule: <；CHEM>； wherein R is a hydrocarbon group having 1 to 24 carbon atoms, OA<；1>； and OA<；2>； are each an oxyalkylene group having 2 to 4 carbon atoms, R and OA<；2>； are the same or different from each other in one molecule, n and m are each average number of moles of the oxyalkylene group added, n represents 0 to 1000, and m represents 10 to 1000.
