<;P>;PROBLEM TO BE SOLVED: To develop a method for introducing a protein into a cell in a high efficiency. <;P>;SOLUTION: A protein is sealed in HVJ-E by a simple method for only mixing HVJ-E with a protein in a 1 tube. Also. the possibility of cell introduction and activity expression of protein that has been regarded difficult hitherto is elucidated by bringing the HVJ-E into contact with cells. <;P>;COPYRIGHT: (C)2008,JPO&INPIT