A manipulator, including: a drive unit for generating a driving force, and a treatment tool that is driven by the drive unit and attachable to and detachable from the drive unit, wherein the treatment tool includes: a distal end having at least one joint driven by the drive unit, a lock unit that is actuated to lock at least one of joints at the distal end, a lock-operating unit for operating the lock unit, and a control unit that is operated such that the lock unit is operated by the lock-operating unit and such that when the drive unit is driven, the drive unit is deactivated, and even with the treatment tool detached from the drive unit, the lock unit keeps on with locking.