An electrically conductive plate of a treatment instrument includes a treating surface and a back surface facing an opposite side of the treating surface, and an electric component is arranged on the back surface of the electrically conductive plate. The electric component is electrically independent from the electrically conductive plate, and a holder supports the electrically conductive plate from the back surface side. A connector is made of a thermoplastic resin, and arranged on either side of and spaced from the electric component in a width direction intersecting with a longitudinal axis. The connector stationarily fixes each end of the electrically conductive plate in the width direction to the holder.
