Abstract: Disclosed herein is a ballast for multiple lamps and a method of manufacturing the ballast. A first coil is wound around a bobbin which has a partition formed in the center portion of an inner space thereof. An insulating sheet is stacked on the first coil, and a second coil is wound around the insulating sheet. Two paired core elements are vertically coupled to each other to form each core. Ends of the core elements disposed outside the bobbin are connected, and ends of the core elements disposed inside the bobbin are spaced apart from each other by the thickness of the bobbin partition, to form a path for magnetic flux.