A package structure including a first semiconductor die, a second semiconductor die, first conductive pillars and a first insulating encapsulation is provided. The first semiconductor die includes a semiconductor substrate, an interconnect structure and a first redistribution circuit structure. The semiconductor substrate includes a first portion and a second portion disposed on the first portion. The interconnect structure is disposed on the second portion, the first redistribution circuit structure is disposed on the interconnect structure, and the lateral dimension of the first portion is greater than the lateral dimension of the second portion. The second semiconductor die is disposed on the first semiconductor die. The first conductive pillars are disposed on the first redistribution circuit structure of the first semiconductor die. The first insulating encapsulation is disposed on the first portion. The first insulating encapsulation laterally encapsulates the second semiconductor die, the first conductive pillars and the second portion.