A stator configured to rotate of a rotor about a central axis includes a first member having a plurality of first concavity portions located in a circumferential direction at a preset interval, each of first concavity portions having a pair of first inner side face and second inner side face whose a circumferential-directional distance therebetween with respect to the central axis becomes narrow from one radial-directional side towards the other radial-directional side with respect to the central axis; and a plurality of second members, each of which having a first protrusion extending along the first inner side face, a second protrusion extending along the second inner side face, and a teeth portion protruding from the first protrusion and the second protrusion to the other radial-direction side, wherein the plurality of second members are formed to corresponding to the plurality of concavity portions, respectively.