Operation part for medical device, ultrasound probe, and endoscope

An operation part for a medical device, the operation part comprising:

• an exterior member that has a distal end part and a base end part and that has a longitudinal axis defined by the distal end part and the base end part;
• at least one operation lever that is provided in a first region, which is a partial region, between the distal end part and the base end part of the exterior member and that is configured to be rotatable about a rotation shaft in a state of being erected on one side in a first direction orthogonal to the longitudinal axis;
• a first outer peripheral surface that is provided in a second region of the exterior member on a base end part side with respect to the first region and that has a normal component directed toward the other side opposite to the one side in the first direction;
• a second outer peripheral surface that is provided in the first region, that has a normal component directed toward the other side in the first direction, and that has a distance to the longitudinal axis equal to or less than a distance from the first outer peripheral surface to the longitudinal axis;
• and
• an indicator part that is provided on a distal end part side with respect to the rotation shaft and on the other side in the first direction.