A fuel injection nozzle for a diesel engine. The fuel injection nozzle may include a plurality of injection hole groups, each having two injection holes respectively. A distance between the two injection holes, an angle between longitudinal axes of the two injection holes and an angle between horizontal axes of said two injection holes of each injection hole group are each set such that fuel sprays injected from said two injection holes will form a single fuel spray cloud after the fuel sprays collide with a side wall of a combustion chamber formed in a top surface of a piston of the engine, and such that the distance between collision points of the fuel sprays will be in a predetermined range in which a penetration force of said fuel spray cloud along a longitudinal direction of said combustion chamber received after collision with said wall of said combustion chamber is at or near a predetermined maximum value.