ENGINE FASTENING STRUCTURE

An engine fastening structure in which a cylinder body and a cylinder head are stacked on and fastened to a crankcase, characterized in that a case side flange portion 3b formed at a crankcase side end portion of the cylinder body 3 is fastened to the crankcase 2 with case bolts 30a, and at least part of head bolts 30c for fastening the cylinder head 4 and the cylinder body 3 together are screwed into the case side flange portion 3b.