Vane members have a space formed therein and a plate spring member is disposed inside the space of the vane members and elastically contacts inner surfaces of the vane members. The plate spring member includes a positioning portion, an elastic contact portion, and a connection portion. The elastic contact portion is divided into a plurality of segments in a length direction of the vane members. The elastic contact portion elastically contacts the inner surfaces of the vane members without any partial contact throughout an entire surface thereof. The elastic contact area between the elastic contact portion and the inner surfaces of the vane members is widened.