PURPOSE: To control an after burning period and improve deterioration of cycle of an engine, by ejecting an auxiliary fluid toward a fuel-air mixture formed by injecting a fuel in a combustion chamber in a later half of a fuel injection period.

CONSTITUTION: A fuel pump 3 is affixed to a base 10 of a fuel injection valve, and a fuel is fed under pressure to a fuel-supplying hole at a predetermined injection timing. On the other hand, a plunger pump 5 for injecting an auxiliary fluid is provided, and the auxiliary fluid is supplied through a check valve 52 at a predetermined timing. A supplying hole 14 for the auxiliary fluid is longitudinally provided in the base 10 of the injection valve and a main body 2 of a nozzle, and another auxiliary fluid nozzle 4 is provided on the peripheral side of the nozzle 8 in the main body 2 of the nozzle, and the auxiliary fluid is ejected, preferably toward a central part thereof, a fuel-air mixture formed by the injection of the fuel through the nozzle 8.