External mechanism for endoscope and endoscope system

An endoscope system comprising:

• an endoscope;
• and
• an external mechanism that can be attached to and detached from an operation portion of the endoscope, wherein
• the endoscope comprises:
• a bending knob provided in the operation portion and configured to bend a bending portion of an insertion portion when the bending knob is turned;
• and
• an endoscope operation control switch arranged in a part of the operation portion and configured to execute a predetermined operation in the endoscope by being operated, and
• the external mechanism includes
• a wheel configured to be engaged with the bending knob to turn the bending knob,
• a motor configured to generate a driving force for rotating the wheel,
• an operation switch configured to output a driving control signal for the motor,
• a container case that contains the wheel and the motor,
• a clamp with which the container case can be attached to and detached from the operation portion,
• a switch case turnably attached to the container case, and configured to be able to turn between a first position that covers a part of the operation portion of the endoscope and a second position away from the first position;
• and
• a dummy switch provided in the switch case, the dummy switch being configured to operate the endoscope operation control switch via the switch case when the switch case is in the first position.