PURPOSE: To enable an engine to be formed compactly with light weight, even if a sufficiently long intake inertia pipe is arranged in order to give intake inertia effect by arranging the intake inertia pipe to the opposite side of a fuel injection pump of the cylinder.

CONSTITUTION: A diesel engine 2 has a vertical axis with a crankshaft 6 arranged in the form of a longitudinal axis, and a fuel injection pump 10 is arranged to one side of a cylinder, the left side. An inlet port 15 which is arranged in the cylinder head area 9 of each cylinder is opened to the right side, each intake inertia pipe 12 is connected to the suction port 15 respectively, and the opening portion of its end portion is opened to the forward position of thid Diesel engine 2.