To establish the engine output to a designated output at a high control speed without hunting by correcting the actuator output, that is, the fuel regulating rack position corresponding to the change of engine output.

An actuator correction amount computing unit 163 compares the actuator output corresponding to the detection value of engine output calculated by an actuator output computing unit 161 with the actuator output set in an actuator output setting device 162 to obtain a deviation to the actuator output from both of the above. This deviation becomes correction amount (y) of actuator output, and the displacement of the fuel regulating rack of a fuel injection pump is corrected by the correction amount (y). Thus, the detection signal L of the engine output is directly input to a governor 16 to correct the actuator output (y) to a designated injection quantity, that is, the total injection quantity of fuel and water, so that the control speed for convertion from only fuel injection to injection of fuel and water is increased.