PURPOSE: To eliminate the necessity of a pressure sensor for atmospheric pressure measurement by controlling the quantity of fuel, while regarding the value of a supercharging pressure detecting pressure sensor as being equal to the atmospheric pressure when the difference between the atmospheric pressure and supercharging pressure during the operation is nearly equal to zero.

CONSTITUTION: The quantity of fuel supplied from an injection valve 8 is corrected first by means of supercharging pressure, which is detected by a pressure sensor 10, and then by the atmospheric pressure. The value of the atmospheric pressure used at that time is that measured by the pressure sensor 10 during the operation, in which the difference between the atmospheric pressure and the supercharging pressure can be regarded as nearly zero, and stored in a register. With this contrivance, a pressure sensor for atmospheric pressure measurement can be eliminated.