A high-frequency treatment instrument that is used with high-frequency electric current supplied from a power source, which includes: a pair of forceps members connected with each other by a rotational axis and an operation wire having a distal end portion which is rotationally connected to proximal end portions of the forceps members and a proximal end portion which is electrically connected with the power source, in which at least one of the pair of forceps members has a conductive electrode portion, and an insulating portion disposed so as to cover at least part of the electrode portion, the operation wire is electrically connected with the electrode portions, and a conductive outer surface of the forceps members, which includes a portion where the operation wire and the electrode portion are electrically connected, located closer to the proximal end portions of the forceps members than the rotational axis of the forceps members is covered by the insulating portion so as not to be exposed.
