A counterweight 40 attached to a crankshaft 38 has a projection 42, which is aligned with and faces an electromagnet 44 attached to a crank casing 46 when the crankshaft 38 is at a preset rotational position of ensuring good startability of an engine 22. Engine stop control starts a power supply to the electromagnet 44 to attract the projection 42 of the counterweight 40 at a timing when the projection 42 of the counterweight 40 is practically aligned with the electromagnet 44, on the condition that the revolution speed of the crankshaft 38 is lowered to or below a preset level immediately before a full stop of rotation of the crankshaft 38. This engine stop control stops the rotation of the crankshaft 38 and desirably holds the crankshaft 38 at the preset rotational position of ensuring good startability of the engine 22.