PURPOSE: To prevent idling knock and to achieve quiet combustion of a diesel engine, by enabling to reduce the ignition delay by employing a simple arrangement in which a fuel collecting portion for collecting a part of sprayed fuel is formed in a fuel spraying region.

CONSTITUTION: At the time of injecting fuel, fuel G ejected from a subsidiary nozzle 2 formed in a nozzle body 3 is collected at a fuel collecting portion 11 and a part of fuel G penetrates into the inner wall surface of a flange portion of a heat shield 4. Here, since the inside of the fuel collecting portion 11 is isolated from the main swirl flow produced in a swirl chamber and its temperature is not so high, all of the collected fuel G is not burnt at the time of expansion stroke of an engine, and a part of fuel remains in the form of liquid or soft carbon. At the time of subsequent compression stroke of the next combusion cycle, part of the residual fuel is vaporized and burnt under a sufficient amount of oxygen, so that the inside of the fuel collecting portion 11 is heated to a high temperature before starting injection of main fuel. Further, since a large amount of activated radicals are produced, fuel G ejected thereafter from a main nozzle 1 is ignited immediately and burnt gently.