A cam element portions is configured such that respective maximum lift portions (lift ending points) of both-side end-face cams thereof are provided at respective phases which are different from each other in a rotational direction and that a maximum value of a length, in an axial direction, between respective cam faces of the both-side end-face cams which are provided at the same phase is set to be a distance, in the axial direction, between a first operational member and a second operational member or smaller. Accordingly, in a valve gear of an engine in which cams operative to control opening/closing of a valve are switchable, it can be properly prevented that a camshaft locks and stop rotating because of an operational malfunction of an operational member or the like.