A method of manufacturing an integrated fan-out (InFO) package includes at least the following steps. A package array is formed. A dielectric layer having a core layer formed thereon is provided. The core layer includes a plurality of cavities penetrating through the core layer. The dielectric layer and the core layer are attached onto the package array such that the core layer is located between the dielectric layer and the package array. A plurality of first conductive patches is formed on the dielectric layer above the cavities.