Abstract: A surgical instrument of the present disclosure includes: a conductive cable member formed into a cable-like shape; a conductive outer shell covering a circumference of the cable member; first and second insulating portions made of materials having higher insulation properties than the cable member and the outer shell; a projecting portion projecting from a projecting insulating portion, which is one of the first and second insulating portions, toward a recessed insulating portion, which is the other, the cable member being inserted into the projecting portion; a conductive leading end portion separated from the recessed insulating portion and the outer shell, the leading end portion being bendable using tension of the cable member with an end portion connected thereto; and a power supply cable in a cable-like shape arranged inside the first and second insulating portions for supplying an electric power from outside to the leading end portion.