A stack type semiconductor package includes a lower semiconductor package including a lower package substrate and at least one lower semiconductor chip disposed on the lower package substrate; an upper semiconductor package including an upper package substrate larger than the lower package substrate and at least one upper semiconductor chip disposed on the upper package substrate; an inter-package connector connecting an upper surface of the lower package substrate to a lower surface of the upper package substrate; and a filler filling in between the lower package substrate and the upper package substrate while substantially surrounding the inter-package connector.