Abstract: The end portion of the side wall of the cylinder head where the rocker cover is attached is extended along the rocker cover, and the position of this end is set at a higher position than the position of the camshaft. The connector tube of the fuel injection nozzle is so formed that it extends obliquely downward at the upper part of the camshaft, facing onto outside from the through hole formed in the extension of the end of the side wall of the cylinder head, to be connected to the fuel supply pipe. Thereby, when the rocker cover is removed, works such as removing the fuel supply pipe from the connector tube and the like are not required, resulting the improvement of the workability. Furthermore, the capacity of the oil separator in the rocker cover can be sufficiently secured.