An omnidirectional wheel is provided. The omnidirectional wheel includes a support unit, a major wheel, a first minor wheel and a second minor wheel. The major wheel is annular and is rotatably disposed on the support unit. The first minor wheel is rotatably disposed on the support unit. The first minor wheel is disposed on one side of the major wheel. The second minor wheel is rotatably disposed on the support unit. The second minor wheel is disposed on the other side of the major wheel. The omnidirectional wheel can easily roll over an obstacle when the omnidirectional wheel rolls laterally or forward.