Provided is an actuator that is able to adjust a ratio of a speed in a rectilinear-direction and a speed in a rotation-direction of an operation element. A differential drive mechanism (110A) includes a front conveyance roller (1112) and a rear conveyance roller (1113) that are able to convey a rod-shaped insertion unit in a long axis direction thereof and rotate the insertion unit about the long axis, and an angle changing mechanism that changes crossing angles of the front conveyance roller and the rear conveyance roller with respect to the insertion unit.
