A fingerprint sensor includes a die, a plurality of conductive structures, an encapsulant, a plurality of conductive patterns, a first dielectric layer, a second dielectric layer, and a redistribution structure. The die has an active surface and a rear surface opposite to the active surface. The conductive structures surround the die. The encapsulant encapsulates the die and the conductive structures. The conductive patterns are over the die and are electrically connected to the die and the conductive structures. Top surfaces of the conductive patterns are flat. The first dielectric layer is over the die and the encapsulant. A top surface of the first dielectric layer is coplanar with top surfaces of the conductive patterns. The second dielectric layer covers the first dielectric layer and the conductive patterns. The redistribution structure is over the rear surface of the die.