Provided are a package-on-package device and a method of fabricating the same. In the device, solder balls may be disposed on two opposing side regions of a package substrate, such that the device can have a reduced size or width. In addition, input/output pads of the logic chip and the solder balls, which need to be directly connected to each other, can be disposed adjacent to each other. As a result, it is possible to improve routability of signals to and from the solder balls and to reduce the lengths of the interconnection lines. Accordingly, it is possible to reduce any signal interference, to increase signal delivery speed, and to improve signal-quality and power-delivery properties.