An integrated fan-out package includes a first redistribution structure, a die, an insulation encapsulation, and a second redistribution structure. The die is disposed on the first redistribution structure. The insulation encapsulation encapsulates the die. The second redistribution structure is disposed on the die and the insulation encapsulation. At least one of the first redistribution structure and the second redistribution structure includes a dielectric layer, a feed line, and a signal enhancement layer. The feed line is at least partially disposed on the dielectric layer. The signal enhancement layer covers the feed line. The signal enhancement layer has a lower dissipation factor (Df) and/or a lower permittivity (Dk) than the dielectric layer.