A high-frequency treatment tool including a flexible tube, an operating wire, a treatment part, a main body, a terminal part, and a main body-operating part, wherein the flexible tube is insertable into a body cavity; the operating wire is insertable through the flexible tube so as to be movable back and forth; the treatment part is arranged on a distal end of the operating wire and is capable of treating biological tissue by applying a high-frequency current; the main body includes a slit hole along an axis direction and is rotatably connected to a base end of the flexible tube; the terminal part includes a power supply terminal to which a power cord that is adapted to supply electric power to the treatment part is detachably connectable and that is rotatably coupled to the main body; the main body-operating part is assembled to the main body along the axis direction thereof and coupled to the main body; the high-frequency treatment tool further comprises: a slider-fixing part that is coupled to the main body, fixes a base end of the operating wire guided from the base end of the flexible tube, and is adapted to slide the operating wire in the axis direction with respect to the main body, and includes a tab insertable through the slit hole; and a slider-gripping part that has a cylindrical shape and is provided so as to encircle at least a portion of an outer peripheral surface of the slider-fixing part and is adapted to slide the slider-fixing part by the operation of the user, wherein the slider-gripping part is rotatably coupled to the slider-fixing part, wherein the terminal part is coupled to a distal end of the main body, such that the terminal part is distal to the main body-operating part and the slider-gripping part, wherein the tab is adapted to fix the base end of the operating wire and is adapted to guide sliding of the slider-fixing part along the slit hole, and wherein the slider-fixing part includes a locking part that is increased in diameter and deformed and engages with the slider-gripping part, rotatably couples the slider-gripping part to the slider-fixing part, and integrally couples the slider-gripping part and the slider-fixing part together in the axis direction of the main body. the flexible tube is insertable into a body cavity; the operating wire is insertable through the flexible tube so as to be movable back and forth; the treatment part is arranged on a distal end of the operating wire and is capable of treating biological tissue by applying a high-frequency current; the main body includes a slit hole along an axis direction and is rotatably connected to a base end of the flexible tube; the terminal part includes a power supply terminal to which a power cord that is adapted to supply electric power to the treatment part is detachably connectable and that is rotatably coupled to the main body; the main body-operating part is assembled to the main body along the axis direction thereof and coupled to the main body; the high-frequency treatment tool further comprises: a slider-fixing part that is coupled to the main body, fixes a base end of the operating wire guided from the base end of the flexible tube, and is adapted to slide the operating wire in the axis direction with respect to the main body, and includes a tab insertable through the slit hole; and a slider-gripping part that has a cylindrical shape and is provided so as to encircle at least a portion of an outer peripheral surface of the slider-fixing part and is adapted to slide the slider-fixing part by the operation of the user, wherein the slider-gripping part is rotatably coupled to the slider-fixing part, wherein the terminal part is coupled to a distal end of the main body, such that the terminal part is distal to the main body-operating part and the slider-gripping part, wherein the tab is adapted to fix the base end of the operating wire and is adapted to guide sliding of the slider-fixing part along the slit hole, and wherein the slider-fixing part includes a locking part that is increased in diameter and deformed and engages with the slider-gripping part, rotatably couples the slider-gripping part to the slider-fixing part, and integrally couples the slider-gripping part and the slider-fixing part together in the axis direction of the main body. a slider-fixing part that is coupled to the main body, fixes a base end of the operating wire guided from the base end of the flexible tube, and is adapted to slide the operating wire in the axis direction with respect to the main body, and includes a tab insertable through the slit hole; and a slider-gripping part that has a cylindrical shape and is provided so as to encircle at least a portion of an outer peripheral surface of the slider-fixing part and is adapted to slide the slider-fixing part by the operation of the user, wherein the slider-gripping part is rotatably coupled to the slider-fixing part, wherein the terminal part is coupled to a distal end of the main body, such that the terminal part is distal to the main body-operating part and the slider-gripping part, wherein the tab is adapted to fix the base end of the operating wire and is adapted to guide sliding of the slider-fixing part along the slit hole, and