A package structure includes an insulating encapsulation, at least one semiconductor die, a redistribution circuit structure, and first reinforcement structures. The at least one semiconductor die is encapsulated in the insulating encapsulation. The redistribution circuit structure is located on the insulating encapsulation and electrically connected to the at least one semiconductor die. The first reinforcement structures are embedded in the redistribution circuit structure. A shape of the package structure includes a polygonal shape on a vertical projection along a stacking direction of the insulating encapsulation and the redistribution circuit structure, and the first reinforcement structures are located on and extended along diagonal lines of the package structure.