An incision instrument includes an insertion section and a manipulation section. The insertion section includes a first insulating member and an incision section inserted within the first insulating member. The incision section includes a tubular shaped first conductive member which has conductivity; a second conductive member disposed in the first conductive member; a contact section provided on an outer circumference surface of the second conductive member; and a second insulating member fixed to a distal end of the first conductive member and having an opening section. The manipulation section includes a manipulation main body section and a handle member. The second insulating member is positioned between the contact section and the first conductive section in a state in which the second conductive member is protruded from the opening section of the second insulating member.