A high-frequency treatment instrument (10) includes a flexible tube (50) for insertion into a body cavity, an operating wire inserted through the flexible tube (50), a treatment element (60) provided at a distal end of the operating wire to treat a diseased part by a high-frequency current, and a manipulating unit (20) attached to a proximal end of the flexible tube (50) to axially move the operating wire to manipulate the treatment element (60), and to rotate the operating wire torsionally about its axis thus rotating the treatment element (60). The manipulating unit (20) includes a main body (22) connected to a high-frequency cable (70), a rotational manipulator (24) attached to a distal side of the main body (22) to rotate the operating wire, and an axial manipulator (26) attached to a proximal side of the main body (22) to axially move thereby causing the operating wire to axially move.
