A layer of thermal insulator is disposed on at least one of an electrically insulating substrate, an adhesive layer and a heat dissipating plate downstream to heating elements on the substrate in a supply direction of a color thermal recording sheet when executing thermal recording. In a manner that the thermal insulator is provided, when executing thermal recording on color thermal recording sheet, heat generated at heating elements is dissipated outside neither from the distal end of the insulating substrate downstream in a supply direction of the insulating substrate nor from the heat dissipating plate through adhesive layer. Since reduction in temperature is suppressed downstream in a supply direction, condensation of steam or vapor is prevented on the protective layer located at topmost of the thermal head, so that printing failure can be avoided.