Disclosed is a physiologically active complex which comprises a proteinaceous part with TNF activity and a high molecular part bound artificially to the N-terminus of the proteinaceous part. The proteinaceous part in the complex has the amino acid sequence of SEQ ID NO:2 where Xaa is a member selected from the group consisting of asparagine, alanine, arginine, serine, threonine, proline, methionine, and leucine; while the high molecular part in the complex is a homopolymer of polyethylene glycol, copolymer of polyethylene glycol, or a derivative thereof.