The present invention is a medical device for treating a biological tissue through use of heat or other energy, wherein the medical device is configured so as to be more minimally invasive in order to reduce patient burden. This medical device is provided with: a supporting member (23) an energy output part (21) for outputting energy for treating a biological tissue a thermal insulation part (22) provided to a back surface of the energy output part (21) and supported by a distal-end side of the supporting member (23) and a thermal conduction member (26) for conducting, to the supporting member (23), heat transmitted from the energy output part (21) to the thermal insulation part (22), the thermal conduction member (26) being provided so as to span between the thermal insulation part (22) and a portion of the supporting member (23) further toward a proximal end than the energy output part (21).
