A treatment-energy applying structure includes a flexible substrate having a wiring pattern having a heat-generation region and a connection region. A heat transfer plate faces a surface of the flexible substrate, and transfers heat to a body tissue. An adhesive sheet, having heat conductivity, is disposed between the flexible substrate and the heat transfer plate to cover the entirety of the heat-generation region and the heat transfer plate. A region of the adhesive sheet protrudes from the heat transfer plate to cover a region of the connection region. A pair of lead wires connects to the connection region outside of the covered region. The adhesive sheet is longer than the heat transfer plate and shorter than the flexible substrate. A gap between an end of the heat transfer plate and the lead wires is longer than a diameter of the lead wires or a thickness of the heat transfer plate.
