A medical instrument used by being introduced into a body and fixed thereto, includes a camera body provided with a fixing section to be fixed to a body wall in the body, an image pickup section incorporated in the camera body that picks up an image of an object to be examined in the body from an observation window formed in the camera body, a contamination removing section provided by being fixed to the camera body, a transparent cover member, an outer surface of which is in contact with the contamination removing section, movably disposed on the observation window and a drive section incorporated in the camera body that drives the cover member to make a sliding contact with the contamination removing section, and can thereby easily and reliably remove deposits stuck to the observation window and obtain a clear observation image even when deposits are being removed.