The types of gasolines having different distillation characteristics and various compositions are identified accurately and rapidly. A pulse voltage is applied for a predetermined time to a liquid type identifying sensor heater including a heater and an identifying liquid temperature sensor provided in the vicinity of the heater. Then, a gasoline to be identified is heated by the heater, and a liquid type is identified with a voltage output difference V0 corresponding to a temperature difference between an initial temperature and a peak temperature in the identifying liquid temperature sensor.