The present invention discloses a cell system, as a host cell to be infected with an F gene-deficient virus, which can constitutively and stably express the F protein, and a method for producing an F gene-deficient virus by utilizing the cell. A non-proliferative human parainfluenza type 2 virus vector is produced by co-culturing an F gene-deficient human parainfluenza type 2 virus with a Vero cell having the F gene of human parainfluenza type 2 virus in such a manner that the F gene is non-inducibly expressed, and isolating viral particles from a culture supernatant.
