Abstract: A medical tube introducer comprising a body having a valve means encased in an inner cavity I, to which a sheath tube connected with the inner cavity I is mounted at the tip, and having a concave or convex portion formed at the center of the rear end and plural concave or convex portions around the center; and a grip member having an inner cavity II and a dilater at the tip portion which is connected with the inner cavity II and is capable of inserting into the inner cavity of the sheath tube in close contact with the inner cavity, and having a convex or concave portion formed at the positions corresponding to the concave or convex portion at the rear end of the body; said valve means being constructed with plural plate-like valve members, each of which valve members has plural slits crossing with each other at the center, and plural of valve members adjacent to each other are overlaid and integrally joined with each other by shifting the positions of said slits except for joining the slits at the center.