Surgical-device rotation mechanism

A surgical-device rotation mechanism comprising:

• a long member formed tubular shape;
• a rotation member that is rotatably supported by a distal end of the long member around a longitudinal axis of the long member;
• an end effector that is fixed to the rotating member;
• a tension convertion member that is disposed inside the long member along the longitudinal axis of the long member and has a distal end to which the rotation member is fixed;
• and
• a rotation restriction mechanism that is disposed between the long member and the tension convertion member,
• wherein the tension convertion member is configured to convert tension applied by pulling of a proximal end into rotation around the longitudinal axis at the distal end, and
• wherein the rotation restriction mechanism is configured to increase or decrease friction between the rotation restriction mechanism and at least one of an inner surface of the long member and an outer surface of the tension convertion member by being operated from a proximal end of the long member so as to restrict or not restrict relative rotation between the long member and the tension convertion member around the longitudinal axis.