PROBLEM TO BE SOLVED: To provide a slip-ring, a differential caster and an electrically-driven wheelchair that can be manufactured at a low cost by downsizing and reducing the number of components.SOLUTION: A slip-ring is provided with rotary terminals 71,78 externally fixed to a diameter-reduced part 53b and slidingly contacting terminals 72,79 arranged along the circumferential direction of the diameter-reduced part 53b and capable of being in sliding contact with the outer peripheral surfaces of the rotary terminal 71,78 from the outside of the radial direction in the diameter-reduced part 53. Supply lines 57a,57b to be electrically connected with a battery are installed in the slidingly contacting terminals 72,79, and the supply lines 57a,57b are extracted from the slidingly contacting terminals 72,79 toward the outside of the radial direction.【課題】小型化、及び部品点数の削減を図り、低コストなスリップリング、差動式キャスタ、及び電動車いすを提供する。【解決手段】縮径部５３ｂに外嵌固定した回転端子７１，７８と、縮径部５３ｂの周方向に沿って配置し、縮径部５３ｂの径方向の外側から回転端子７１，７８の外周面に摺接可能な摺接端子７２，７９と、を備え、摺接端子７２，７９に、バッテリに電気的接続する供給線５７ａ，５７ｂを設け、供給線５７ａ，５７ｂを、摺接端子７２，７９から径方向の外側に向けて引き出すことを特徴とする。【選択図】図５
