A technique using a trocar including a retractable camera in which fogging and organic matters are removed to clean a lens of the camera. The trocar includes a pipe portion and a head portion. The pipe portion includes a side opening portion. According to rotation of a changing over mechanism and a shaft, the retractable camera rotates such that the camera is changeable between a stored position and a deployed position by passing through the side opening portion. A wiper blade is fixed to an end face of the side opening portion on a tip side of the trocar. When the retractable camera rotates, a tip of the wiper blade contacts a camera lens in a deformable manner.
