A device with both functions of wireless power transmitter and wireless power receiver and a circuit thereof are provided in the present invention. The device with both functions of wireless power transmitter and wireless power receiver and the circuit thereof use the same winding for performing the energy output and the energy receiving function. In addition, in order to use the same winding for performing the energy output and the energy receiving function, the present invention adopts full bridge topology. However, two lower switches are controlled by the resonant circuit when the device is in the energy receiving mode. The upper switches are not only for receiving the power voltage, but also for rectifying the energy received from the winding to output to the device with both functions of wireless power transmitter and wireless power receiver.