A wireless power supply device comprises a transmitting coil assembly and a receiving coil assembly. The transmitting coil assembly includes a first ferrite core having a receiving chamber with an opening and a transmitting coil disposed in the receiving chamber of the first ferrite core. The receiving coil assembly is adapted to be moved into the receiving chamber through the opening of the receiving chamber and located at a predetermined position in the receiving chamber. The receiving coil assembly is electromagnetically coupled with the transmitting coil assembly.