A curving section is always disposed in a projection plane of a probe main body section, when the probe main body section is seen along a longitudinal axis from a proximal end toward a distal end. The curving section includes a first bending surface which bends relative to a peripheral surface of the probe main body section to approach the longitudinal axis, thereby intersecting the longitudinal axis； a second bending surface which bends relative to the first bending surface toward a bending direction of the first bending surface and a direction away from the longitudinal axis； a third bending surface which bends relative to the second bending surface toward a direction to approach the longitudinal axis on a side reverse to the bending direction of the first bending surface, and extends toward an extension line of the first bending surface. The curving section includes a first treating surface which bends relative to the third bending surface in the bending direction of the first bending surface, and a treating region which is positioned on the extension line or positioned on a side opposite to the longitudinal axis with respect a boundary that is the extension line.
