A package structure includes a lower substrate, substrate connection terminals on the lower substrate, a semiconductor package on the substrate connection terminals, the semiconductor package including a package substrate and a first encapsulant covering the package substrate, first underfills between the lower substrate and the semiconductor package, the first underfills covering corner portions of the semiconductor package, as viewed in a plan view, and covering at least one of the substrate connection terminals, and a second underfill between the lower substrate and the semiconductor package, the second underfill covering a side surface of the semiconductor package in a plan view.