It is an object of the present invention to provide an engine control apparatus for detecting a voltage abnormality caused in a power supply thereof at low cost. An engine control apparatus for controlling an engine, includes: power supply voltage detecting unit for detecting a power supply voltage of a battery mounted on a vehicle as a power supply, which supplies the engine control apparatus with power; backup power supply voltage detecting unit for detecting a backup power supply voltage of a backup power supply, which supplies the engine control apparatus with power from the battery via a different path; voltage difference calculating unit for calculating a voltage difference between the power supply voltage and the backup power supply voltage; and power supply voltage abnormality determining unit for determining that there is an abnormality in the power supply voltage when the voltage difference is not within a predetermined range.