An engine having an engine case on one side of which a V-belt type of continuously variable transmission is provided, the CVT being placed in a transmission case and constituted that a V-belt is routed around a drive pulley and a driven pulley, the drive pulley being attached to one end of a crankshaft, the driven pulley being attached to one end of a transmission shaft parallel to the crankshaft, characterized in thatthe crankshaft is supported for free rotation with the engine case, one end of the crankshaft is projected in cantilever fashion from the engine case into the transmission case, the drive pulley is attached to the projected portion, and the transmission case is made as a component separate from or independent of the engine case and supported with the engine case so that a space is present between the engine case and the transmission case.