Provided is a high-frequency treatment tool including: a sheath； an electrode member being advancable and retractable in the sheath； a distal end member disposed at a distal end of the sheath, wherein the electrode member includes a columnar portion； an electrode distal end portion provided at a distal end of the columnar portion and radially extending in an outward direction； and a stopper portion disposed at a proximal end side of the columnar portion, the stopper portion having the shape of a solid of revolution about a center axis of the electrode member, the distal end member has a tapered inner surface narrowing toward the distal end, a recessed portion is formed in a portion of the stopper portion, the electrode distal end portion has a small-diameter portion recessed in a radial direction, and the channel and the small-diameter portion are located at the same position in the circumferential direction.
