PURPOSE: To reduce cost with high productivity by adopting a structure to join inner parts to each other by adhesives without using a large number of screws and nuts for reducing numbers of parts and processings.

CONSTITUTION: In a two stroke cycle engine (a), bolts, screws, and nuts are not used at all for assembling its component parts. For example, a cylinder block 4 with a crank case 5 and half-divided members 5a and 5b of the crank case 5 with each other are combined by epoxy adhesives. In the combining structure between the cylinder block 4 and the crank case 5, a large adhesive area is taken in overlapping joined parts 6 and 7 for promoting the adhesive effect. For attaching half-divided members 5a and 5b of the crank case 5 with each other, a fit-in structure between a female rail 8 and a male rail 9 is adopted at the joining part to promote the adhesive effect and keep high sealing effect. Besides, the use of a knock pin 10 permits to simplify positioning at attaching.