PURPOSE: To prevent deterioration of burning condition by prohibiting the motion of a control rack of one fuel injection pump arranged on each bank of Diesel engine having two banks in predetermined operational region.

CONSTITUTION: In a V type Diesel engine 1 having two banks 2, 2', fuel injection pumps 3, 3' for controlling the fuel supply by moving the control racks 3a, 3a' through D.C. solenoids 4, 4' are arranged at the side of each bank 2, 2'. Here, CPU13 will decide the load condition on the basis of output signals from a position detector 7 for detecting the operational position of throttle lever 8 as an electric signal S2 and a rotary speed detector 9 for producing an electric signal S3 having frequency corresponding with the engine rotation. Upon decision that the engine is under light load, it is controlled such that only one control rack 3a is operated through a solenoid drive circuit 19.