A baby endoscope which forms a medical device includes: a rotary member； an exterior member which rotatably holds the rotary member about a predetermined rotation axis, houses the rotary member in the exterior member, and has a surface which is brought into contact with a portion of an outer peripheral surface of an operation section of a mother endoscope on an outer peripheral portion； and a bending operation lever mounted on the rotary member, and is disposed within a width of the exterior member in a direction of the rotation axis when the exterior member is viewed in a direction orthogonal to the rotation axis.
