Provided are transmembrane complexes that contain a protein transduction domain (PTD) from the N-terminus of IgE-dependent histamine-releasing factor (HRF) and a target substance that is to be delivered into a cell. Also provided are nucleic acid molecules encoding the transmembrane complex and methods of delivering the target substance into a cell interior by contacting the transmembrane complex with a cell. Also provided are transfection kits containing the PTD and the target substance.