A rear wheel drive device including omnidirectional wheels applied to a transportation tool such as a wheelchair or a cart is provided. An omnidirectional wheel has openings at both ends, end caps are fixed to both ends of a hollow hub, an electric drive mechanism is provided in the hub, and both ends of the electric drive mechanism have end caps. The hub is pierced and supported, and at least two rows of rollers are assembled to the hub so as to be movable along the circumferential direction. In the rear wheel drive device A, a support arm 51 extending in the axial direction along the housing is provided symmetrically at one end of the housing 50, and an omnidirectional wheel is installed in a space between the two support arms. The other end of the housing is connected to the support arm, and the other end of the housing is hinged to the rear of the transportation tool. The omnidirectional wheel contacts the ground by gravity, and includes a battery and a controller for an electric drive mechanism in the housing. [Selection] Figure 3【課題】車椅子またはカートなどの輸送ツールに適用する無指向性車輪を含む後輪駆動装置を提供する。【解決手段】無指向性車輪Ｂは、両端に開口を有し、中空ハブの両端開口にそれぞれエンドキャップが固定され、ハブ内に電動駆動機構が設けられ、電動駆動機構の両端はエンドキャップを貫通して支持され、ハブには円周方向に沿って少なくとも２列のローラーが移動可能に組み立てられる。後輪駆動装置Ａは、ハウジング５０の一端にハウジングに沿って軸方向に延びる支持アーム５１が対称に設けられ、無指向性車輪が２つの支持アームの間の空間内に設置され、電動駆動機構の両端がそれぞれ支持アームに接続し、ハウジングの他端は輸送ツールの後部にヒンジ接続される。無指向性車輪は重力により地面と接触し、ハウジング内にバッテリと、電動駆動機構のコントローラを含む。【選択図】図３
