PURPOSE: To inject water to a combustion chamber of an engine to lower the combustion temperature and lessen the generation of NOx, black smoke, HC and CO without producing misfire in a water injection valve for injecting water and fuel and Diesel engine with the water injection valve.

CONSTITUTION: A water injection hole 80 and fuel injection hole 62 are respectively independently provided and constituted such that fuel injected from the fuel injection hole 62 is propagated as flame to the downstream side of swirl generated in a combustion chamber and the fuel is injected toward a portion subjected to combustion with high temperature while water is injected from the water injection valve 80.