The object of the present invention is to provide a method of efficient delivery into a brain and central nervous system, and to provide a method of efficient delivery with a viral envelope. The present invention provides a system for introducing a biomolecule into a cell comprising A) a biomolecule; B) a viral envelope; and C) glycosaminoglycan. Further, the present invention provides a method for delivering a biomolecule into a brain, comprising the steps of: A) transiently closing an artery of the head portion or cervical portion; and B) introducing a biomolecule into the brain during the closing of the artery of the head portion or the cervical portion.