To bring an electrode ring and a feed brush into contact with each other only when conducting is necessary between a rotary table and a fixed platen, and in other conditions, to allow the rotary table to rotate with the electrode ring and the feed brush being separated from each other.

A slip ring A comprises a rotary table 1 rotating together with a rotary main axis 7, a fixed platen 2 disposed so as to face the rotary table 1, and a brush unit 5 provided with feed brushes 4 which face and are contact with electrode rings 3 disposed on the rotary table 1. The brush unit 5 is supported on the fixed platen 2 such that the feed brushes 4 are separably attached to the electrode rings 3. Further, an expandable member 6 is provided between the brush unit 5 and the fixed platen 2 so as to displace the brush unit 5 to the rotary table 1 and to bring the feed brushes 4 into contact with the electrode rings 3. Only when conducting is necessary between the fixed platen 2 and the rotary table 1, the feed brushes 4 are brought into contact with the electrode rings 3 by the expandable member 6.