A medical instrument includes an insertion part and a driving mechanism coupled to the insertion part. The insertion part has a treatment part, a joint part configured to support the treatment part and to be capable of changing a direction of the treatment part, and a driving force transmission part connected to the joint part and configured to transmit a driving force to the joint part. The driving mechanism has a driving force generator that is connected to the driving force transmission part and is configured to generate the driving force. A storage part configured to store the treatment part in the joint part by the driving force transmitted from the driving force generator to the joint part via the driving force transmission part is formed at the joint part.
