In an engine of a compression-ratio variable type, a subsidiary rod and a piston connected to a crankshaft are connected to each other through a connecting rod, and an eccentric shaft mounted at an eccentric location on a support shaft turnably carried in an engine body and the subsidiary rod are connected to each other through a control rod, so that the compression ratio of the engine is changed by changing the turned position of the support shaft. The engine further includes a one-way clutch mounted between the support shaft and the engine body for limiting the direction of turning of the support shaft. The turned position of the support shaft is limited selectively at a plurality of points by a turned-position limiting means, and a load applied to at least one of the support shaft and the turned-position limiting means is moderated by buffering means.