A fuel injection nozzle disposed in a center of a reentrant cavity combustion chamber has first and second nozzle hole groups whose inclination angles with respect to a cylinder center axis line are different. A nozzle hole diameter of the second nozzle hole group is larger than that of the first one. First and second nozzle holes are alternately arranged in a circumferential direction. A glow plug projects, in a height direction of the cylinder, up to a height of a spray center axis line (F2) of the second nozzle hole directed at a lower side. Therefore the glow plug can contact fuel masses formed by sprays from both the first and second nozzle holes. The glow plug is positioned between spray center axis lines (F1, F2) in the circumferential direction, and positioned at a swirl downstream side of spray center axis line (F2).