Abstract: Manufacture of a metal rotor for a trimmer capacitor using cold forging or casting conventionally requires a metal mold to be exclusively used for the metal rotor, which incurs costs associated with the fabrication and maintenance of the mold. According to the invention, however, a metal rotor can be obtained by etching instead of cold forging or casting. Specifically, a metal plate is provided which has a principal surface with a predetermined degree of smoothness for a surface of a rotor electrode. The metal plate is selectively etched using resists, to form a step portion, a driver groove and a circumferential surface for the rotor electrode, which are the components of the metal rotor.