An apparatus for detecting abnormality for a fuel property detecting apparatus according to the present invention includes the fuel property detecting apparatus having a sensor part provided on a fuel channel, temperature detecting means for detecting the temperature of the fuel in the vicinity of said sensor part, a heater capable of raising the temperature of the fuel in the vicinity of the sensor part, and abnormality determining means for determining whether or not there is an abnormality in the fuel property detecting apparatus based on the temperature detected by the temperature detecting means when the heater is activated. The abnormality determining means includes fuel flow abnormality determining means for determining whether or not there is an abnormality in the flow of the fuel in the vicinity of the sensor part and failure determining means for determining whether there is a failure of said fuel property detecting apparatus itself.