A fuel evaporator for use in a fuel entry system of an internal combustion engine comprises a heating element of ceramics having a positive temperature coefficient of resistance, a thermally conductive covering plate which covers the heating element in the fuel entry system and a connecting means which electrically connects the heating element to an electric power source.The connecting means comprises two electrifying routes and switching means which breaks one electrifying route or selectively connects the two electrifying routes in parallel or in series in accordance with the driving condition of the engine.The fuel droplets falling within the fuel entry system can be evaporated by only a small amount of electric power with high efficiency.And by controlling the electric power consumed by the fuel evaporator, the starting condition of the engine can be maintained good.