A medical device that can perform plural actions by a single operation and is excellent in operability includes a catheter that is insertable into a living body, a sandwiching portion and a needle positioning portion that are disposed in the catheter so as to be able to advance and retract. A slide portion is operable such that the sandwiching portion and the needle positioning portion advance and retract simultaneously, and an action switching portion causes the sandwiching portion to advance and retract in tandem with or independently of the slide portion by the advance and retraction of the slide portion.