The invention provides a trocar (D) for penetrating body tissue and being placed, which allows for shortening the time required to seal an opening, regardless of the size of the opening. In a first trocar used in performing surgery, an incision member (A) is detachably inserted into the cannula portion (10) and a cutting blade (2) with a shape of a nearly straight line is formed at the tip. In a second trocar, the tip part of the cannula portion that detachably inserts the incision member has a slanting cut end (12), and the slanting cut end is formed in a tapered shape.
