A package structure includes a die, an encapsulant, and a first redistribution structure. The die has an active surface and a rear surface opposite to the active surface. The die includes a ground plane within the die. The encapsulant encapsulates the die. The first redistribution structure is over the active surface of the die. The first redistribution structure includes an antenna pattern electrically coupled with the ground plane. The antenna pattern is electrically connected to the die.