A gripping unit includes a supporting section in which at least its entire surface is made of an insulating material, and a swing section swingable about a swing axis relative to the supporting section. The swing section includes a jaw-side facing surface opposed to a treatment section, and a jaw-side electrode section functioning as an electrode when high-frequency energy is transmitted. The support member covers the swing section from a distal direction, both of width directions, and an open direction of the jaw, and the swing section is externally exposed only on the jaw-side facing surface.
