A treatment portion of a treatment device includes a pair of jaws, an energy emitter, a base having has electric insulation, an outer edge, first to third channels and a support portion. The first channel is formed by the energy emitter, the base, and the outer edge, fluid emanating from the living tissue of the treatment target flows into the first channel. The second channels are provided between the base and the outer edge. The third channel is provided between the outer edge and the energy emitter to allow the fluid emanating from the living tissue to flow toward the first channel. The support portion couples the base to the outer edge so that the fluid emanating from the living tissue flows into the first channel, and supports the living tissue to prevent it from coming into the first channel when it is held between the pair of jaws.
