PURPOSE: To obviate the sharp rise in the temperature of burning so as to reduce the NOx-content and combustion noise in the low rotation and low load range, by providing a fuel passage with a plurality of branch passages having different passage diameters and a pilot valve for changing over or shutting them in accordance with the fuel pressure.

CONSTITUTION: When injection pressure rises, a valve 12 is lifted, and a small amount of a fuel is injected from an injection orifice 14, and when the fuel pressure at a valve head reaches the open valve pressure, a valve body 57 is moved to shut the communication of passages 50a, 50b. As a result, the injection pressure lowers quickly, and a nozzle 10 is closed to suspend the injection. The fuel pressure moves further the valve body 57 to cause it to abut against a stopper 62 and passages 51a, 51b comes in communication with each other. The fuel pressure in a pressure chamber 7 is transmitted via the passages 51a, 51b to a needle chamber 11, the injection pressure is increased, and the nozzle 10 is opened to inject a large quantity of the fuel. Thus, the burning by the pilot jetting is smoothly led to the main injection burning, and the abrupt generation of heat in the burning chamber can be obviated.