A yoke housing includes a tubular case and a flange. The tubular case is formed from a metal sheet in a drawing process. The flange is formed at an end of the tubular case. The flange has a width in the lateral direction that is equal to the outer diameter of the tubular case. The flange has a base including beads and a thick portion. Each of the beads is formed by compressing the base. A portion of the base in which the beads are not formed defines a thick portion. The thick portion is located at a middle portion of the flange in the lateral direction. The beads are located on opposite sides of the thick portion in the lateral direction.