A rear derailleur of a bicycle includes a fixing portion connected to a frame of the bicycle, a linkage assembly pivotally connected to the fixing portion, a moving portion pivotally connected to the linkage assembly, a chain guide assembly connected to the moving portion, a driving assembly, a rechargeable battery for providing an electrical energy required for the motor, a coil, and a wireless charging circuit for receiving an electric power of the coil for charging the rechargeable battery. The driving assembly includes a motor including and a driving gear assembly connected to the linkage assembly. The motor includes an output shaft for driving the driving gear assembly and for driving the linkage assembly to pivot via the driving gear assembly, thereby to drive the moving portion and the chain guide assembly to move. The coil receives an external charging power and is disposed on the fixing portion, the moving portion, or the linkage assembly.