A manipulator (2), includes a longitudinal portion (15) configured to have a distal end and a proximal end, the longitudinal portion being inserted into a body cavity from the distal end； a rotation driving unit (19) connected to the longitudinal portion (15) and configured to rotate the proximal end of longitudinal portion (15) about a longitudinal axis of the longitudinal portion (15) as a rotary axis； and an uneven portion disposed on an outer circumference surface in the vicinity of the distal end of the longitudinal portion (15), the uneven portion being configured along a helix with the longitudinal axis of the longitudinal portion (15) as a helical axis, wherein the distal end of the longitudinal portion (15) and the uneven portion are rotatable about the longitudinal axis following the rotation of the proximal end of the longitudinal portion (15) when the proximal end is rotated by the rotation driving unit (19).
