A rotary terminal mechanism in which a first electroconductive ring is inserted, under a slightly collapsed state, between the circular internal peripheral surface of a first outside electrode and the circular external peripheral surface of a first inside electrode that are arranged concentrically. The first electroconductive ring is kept contacting the first outside electrode and the first inside electrode by the elastic restoring force. When the first outside electrode and the first inside electrode rotate relatively, the first electroconductive ring rolls along the circular internal peripheral surface and the circular external peripheral surface while being kept pressed against these surfaces by the elastic force. Consequently, electrical connection is formed constantly between them even if the first outside electrode and the first inside electrode rotate relatively. A rotary terminal mechanism of simple structure requiring fewer components and being advantageous to miniaturization can thereby be attained.