The invention relates to a surge protection device, comprising at least one surge arrester and one thermally trippable switching device connected in series with the surge arrester, wherein the above-mentioned means form a structural unit and the thermal tripping means is arranged in the region in which heating of the surge arrester is to be expected on overloading thereof. The thermal tripping means is in the form of a stop part through which there is no operating or surge current flowing and which effects or enables unlatching of the switching device in the case of thermal overload. Furthermore, the stop part is coupled thermally and mechanically to a surface side of the surge arrester and blocks the movement path of a mechanically prestressed unlatching slide. In accordance with the invention, a contact platelet is inserted in the unlatching slide, said contact platelet producing an electrical connection between elements of the switching device and, with unlatching, the contact platelet is subjected to a shifting movement resulting in an interruption to the series circuit and movement of the unlatching slide into the space previously assumed by the contact platelet, wherein at least the section of that region of the unlatching slide which separates the elements of the switching device is insulating.