An endoscopic instrument (1, 21, 31, 41) comprising: an incising section configured to be inserted into a body cavity endoscopically for incisional intervention; a wire having a distal end connected to the incising section; a sheath, made from insulative material, for allowing the wire to pass therethrough; a main body in which a proximal end of the sheath is fixed thereto, the proximal end being capable of freely rotating in a circumferential direction; a slider, in which a proximal end of the wire is fixed thereto, the slider being disposed slidably in an axial line direction of the main body; a stopper (6, 32, 42), provided between a proximal end of the incising section and a distal end of the wire, for projecting outward radially relative to the wire; a first-distal-regulation section, provided to a distal end of the sheath, for regulating distal sliding movement of the wire by making contact with the stopper (6, 32, 42); and a second-distal-regulation section, provided distally relative to the first-distal-regulation section, for regulating distal sliding movement of the wire by making contact with the stopper (6, 32, 42), wherein the stopper (6, 32, 42) is capable of moving between the first-distal-regulation section and the second-distal-regulation section by rotating the main body relative to the sheath around an axial line by a predetermined rotational angle, and the incising section can be maintained at two different projection lengths based on the stopper (6, 32, 42) making contact with the first-distal-regulation section or the stopper making (6, 32, 42) contact with the second-distal-regulation section. an incising section configured to be inserted into a body cavity endoscopically for incisional intervention; a wire having a distal end connected to the incising section; a sheath, made from insulative material, for allowing the wire to pass therethrough; a main body in which a proximal end of the sheath is fixed thereto, the proximal end being capable of freely rotating in a circumferential direction; a slider, in which a proximal end of the wire is fixed thereto, the slider being disposed slidably in an axial line direction of the main body; a stopper (6, 32, 42), provided between a proximal end of the incising section and a distal end of the wire, for projecting outward radially relative to the wire; a first-distal-regulation section, provided to a distal end of the sheath, for regulating distal sliding movement of the wire by making contact with the stopper (6, 32, 42); and a second-distal-regulation section, provided distally relative to the first-distal-regulation section, for regulating distal sliding movement of the wire by making contact with the stopper (6, 32, 42), wherein the stopper (6, 32, 42) is capable of moving between the first-distal-regulation section and the second-distal-regulation section by rotating the main body relative to the sheath around an axial line by a predetermined rotational angle, and the incising section can be maintained at two different projection lengths based on the stopper (6, 32, 42) making contact with the first-distal-regulation section or the stopper making (6, 32, 42) contact with the second-distal-regulation section.