Abstract: A valve gear comprises a valve 1 having a valve element and a valve stem, and an actuator having a driving shaft for operating the valve element of the valve. A connecting portion 7 is provided on either the valve or the actuator. A sleeve having a smooth inner surface is fixedly or rotatably fitted in a bore formed in the connecting portion 7 so as to slidably receive the valve stem and the driving shaft and slidably contact the inner smooth surface of the sleeve with outer surfaces of the valve stem and the driving shaft. The valve stem and the driving shaft inserted into the sleeve through the opposite ends, of the sleeve are provided at their end portions with respective coupling portions, so that the stem and the shaft are able to engage with each other only at the particular one point of relative rotation of the stem and the shaft.