A wireless charging device for wirelessly transmitting electric power to an electronic device includes a housing, a system board within the housing and including a power amplifier, a shield-can within the housing with a separation distance between a top of the housing and a top of the shield can, a transmission resonator between the top of the housing and the top of the shield-can for simultaneously generating a vertical magnetic field and a horizontal magnetic field, and a sheet provided between the shield-can and the transmission resonator for shielding the system board and the transmission resonator from each other's electromagnetic fields, wherein the electromagnetic fields comprise the vertical magnetic field and the horizontal magnetic field generated by the transmission resonator and an electromagnetic field generated by the system board.