A stack package includes a first sub-package and a second sub-package stacked on the first sub-package. The first sub-package includes a first through mold via (TMV) for connection spaced apart from a first semiconductor chip in an X-axis direction, a first TMV for bypass spaced apart from the first semiconductor chip in a Y-axis direction, and a first redistribution line (RDL) pattern connecting the first semiconductor chip to the first TMV for connection. The second sub-package includes a second TMV for connection spaced apart from a second semiconductor chip in the Y-axis direction and another RDL pattern connecting the second semiconductor chip to the second TMV for connection. the second sub-package is stacked on the first sub-package such that the second TMV for connection is connected to the first TMV for bypass.