In a living body introduction apparatus, an inner rotating cylinder is covered with a stretchable cover having an inner circumferential length shorter than an outer circumferential length of the inner rotating cylinder. A portion of the cover pushed out in a protruding form by a roller disposed on an outer circumferential surface of the inner rotating cylinder enters a circular groove formed inside an outer rotating cylinder. Rotation of the inner rotating cylinder circularly moves the protruding portion on the outer circumferential surface. The protruding cover portion pushes the circular groove to rotate the outer rotating cylinder.
