In order to more reliably catch and eject even a gallstone trapped in a stepped portion obliquely formed at a boundary between the bile duct and the duodenal papilla, an endoscope treatment tool (1) according to the present invention includes: a sheath (2) having a lumen extending along the longitudinal axis； a basket section (4) that protrudes from the lumen and that has at least one elastic wire (4a)； and an operating wire (5) for advancing/retracting the basket section in the longitudinal direction of the sheath, wherein the elastic wire has: a maximum outer diameter section where the outer diameter of the basket section is largest between the distal end and the proximal end of the elastic wire； a first maximum section that, in a lateral view from a direction orthogonal to a normal from the maximum outer diameter section to the central axis of the basket section, is largest on the opposite side of the central axis from the maximum outer diameter section between the maximum outer diameter section and the proximal end of the elastic wire； and a second maximum section that is largest at a position away from the normal between the maximum outer diameter section and the first maximum section, and in the front view of the basket, the first maximum section is located on the opposite side of a straight line, which is orthogonal to the normal at the central axis, from the maximum outer diameter section side.
