Abstract: The present invention relates to a conductive polymer composition having PTC properties, that is, a PTC composition, and a PTC device comprised thereof, in particular, it relates to a PTC composition and a PTC device comprising thereof, wherein the PTC composition comprises: a) at least one crystalline thermoplastic olefin-based polymer and at least one rubber-based polymer resin containing unsaturated group; and b) conductive particles dispersed in a polymer matrix formed of component a). The PTC device comprising the PTC composition makes it possible to construct circuit protecting devices which can stably maintain their initial resistance value in spite of repeated current cycling by short-circuit.