A variable stroke engine has a crankshaft, a camshaft, and a rotational shaft, having an eccentric shaft, which are rotatably supported in a crankcase so as to have axes parallel to one another. A connecting rod is connected, at one end portion thereof, to a piston by a piston pin, and a control rod is connected, at one end portion thereof, to the eccentric shaft. The other end portion of the connecting rod and the other end portion of the control rod are linked to each other by a link member rotatably supported on the crankshaft. A rotative power of the crankshaft is transmitted to the camshaft and the rotational shaft, respectively. A timing driving wheel transmitting the rotative power to the camshaft side is mounted on the crankshaft, and a timing driven wheel driven by the timing driving wheel is mounted on the rotational shaft.