A Positive Temperature Coefficient (PTC) rod assembly and a preheater incorporating the same. The PTC rod assembly includes a negative terminal and a positive terminal coupled with opposite surfaces of a PTC rod, the negative and positive terminals being spaced apart from and parallel to each other; a PTC element interposed between and being in electrical contact with the negative and positive terminals, an insulating film adhered to exposed portions of the negative and positive terminals, which are coupled with the PTC rod, and a PTC rod housing. The PTC rod housing stores the PTC rod therein, the negative and positive terminals and the PTC element coupled with the PTC rod, and the insulating film adhered to the PTC rod. The PTC rod assembly is used stably even when a high voltage is applied thereto. A short circuit is prevented from occurring between the two terminals due to contact.