Two turbochargers are arranged vertically near a one side of a crank-shaft direction at a one-side face of an engine body so that the large-size turbocharger is located above the small-sized turbocharger, and an exhaust-gas purification device is arranged an open space made on the other side of the crank-shaft direction so that its exhaust inlet is located above and its outlet is located below. Accordingly, the turbochargers and the exhaust-gas purification device can be arranged compactly and the layout of some devices around the engine can be facilitated.