Internal flow in the diesel injection nozzle of a ole type was observed by using a tenfold water flow model and polystyrene tracer to investigate the relationship between the spray angle and the flow pattern in the suck volume of the nozzle. The three kinds of model nozzles, "90°-Needle", "Flat-Needle" and "Cylindric-Needle" were made of transparent acrylic plastic. The model nozzles were operated with water under conditions which gave a Reynolds number similar to that of a diesel nozzle at the exit of the nozzle hole. When the needle lift was very small, the high velocity of the inlet flow caused large turbulence in the suck volume and a wide spray angle. The nozzle of the "Flat-Needle" type had a tendency to produce an unsteady flow. This unsteady flow also caused turbulence in the suck volume and a wide spray angle.