Provided is a semiconductor package comprising a lower package that includes a lower substrate and a lower semiconductor chip, an interposer substrate on the lower package and having a plurality of holes that penetrate the interposer substrate, a thermal radiation structure that includes a supporter on a top surface of the interposer substrate and a plurality of protrusions in the holes of the interposer substrate, and a thermal conductive layer between the lower semiconductor chip and the protrusions of the thermal radiation structure.