To provide a rotary electrical part having proper productivity and which is low cost.

The rotary electrical part includes a rotary body 6 made of a synthetic resin, and an upper case 4 made of a synthetic resin material for holding this rotary body 6. The rotary body 6 and the case 4 are formed, in a state to be coupled by a coupling part 7 with each other. Since the rotary body 6 is separated from the case 4 by cutting the coupling part 7 and is set rotatable, the case 4 and the rotary body 6 are constituted of a single part, both can be simultaneously manufactured. The electrical part has the proper productivity and is low in cost. Further, the case 4 and the rotary body 6 do not need an assembling work as in prior art, the assembling work cost can be reduced, and low cost parts are obtained.