A connection system of semiconductor packages includes: a printed circuit board; a first semiconductor package disposed on a first surface of the printed circuit board and connected to the printed circuit board through first electrical connection structures; a second semiconductor package disposed on a second surface of the printed circuit board and connected to the printed circuit board through second electrical connection structures; and a third semiconductor package disposed on the first semiconductor package and connected to the first semiconductor package through third electrical connection structures. The first semiconductor package includes an application processor (AP), the second semiconductor package includes a memory, and the third semiconductor package includes a power management integrated circuit (PMIC).