A circuit board includes a first insulating structure, a first redistribution layer, a second insulating structure, and a second redistribution layer. The first insulating structure has an upper surface and includes a first liquid crystal polymer layer. The first redistribution layer is disposed on the upper surface of the first insulating structure. The second insulating structure is disposed on the upper surface of the first insulating structure and covers the first redistribution layer. The second insulating structure has a top surface opposite to the upper surface and includes a second liquid crystal polymer layer. The second redistribution layer is disposed on the top surface of the second insulating structure.