An ultrasonic treatment device includes a first path defining portion defining a first path that is opened at an opening position at a distal end portion of a probe, and a second path defining portion defining a second path communicating with the first path outside a treatment unit. The first path is extended to a bending position located to a distal direction side of a first coupling region in the probe along a longitudinal axis, and is extended to an outside of the treatment unit through an outer peripheral portion of the probe by bending at the bending position. The second path defining portion is extended in a fixed handle of a handle unit from the outside of the treatment unit along a handle extending direction.
