A medical instrument includes: an image pickup unit incorporated in a medical instrument body for picking up an image of the subject to be examined from an observation window; an airflow generating unit provided rotatably with respect to the medical instrument body so as to cover the image pickup unit by a covering unit having an opening formed therein, the airflow generating unit being configured to generate an airflow for preventing adherents from sticking to the observation window, by rotation of the covering unit; a fixing unit for indwelling and fixing the medical instrument body inside the subject to be examined; and a drive unit incorporated in the medical instrument body, for driving the airflow generation unit.