A wireless power transmitter that transfers power to a wireless power receiver includes a coil assembly comprising first and second bottom coils placed adjacent to each other in a line and each consisting of a single layer of 11 turns and a top coil stacked on the first and second bottom coils and consisting of a single layer of 12 turns; a series capacitance; a shielding extending to at least 2 mm beyond an outer boundary of the coil assembly, has a thickness of at least 1.5 mm and being composed of Mn—Zn; and a full-bridge inverter driving each of coils included in the coil assembly individually.