A high-frequency treatment instrument includes an electrode having an outer surface, a high-frequency electric current is applied to a target of treatment through the outer surface of the electrode. A coating covers the outer surface of the electrode, and is formed from a conductive mixture obtained by mixing a non-conductive material and a conductive material. The conductive material contained in the mixture forming the coating includes first elements, and second elements each of which has a different shape from each of the first elements.
