A semiconductor device including a first substrate having first and second surfaces, multiple first mounting pads formed on the first surface of the first substrate and for mounting a first semiconductor element on the first surface of the first substrate, multiple first connection pads formed on the first surface of the first substrate and positioned on the periphery of the multiple first mounting pads, a second substrate formed on the first substrate and having first and second surfaces, the second substrate having a second penetrating electrode which penetrates through the first and second surfaces of the second substrate, multiple second mounting pads formed on the first surface of the second substrate and for mounting a second semiconductor element, and a conductive member formed on one of the first connection pads and electrically connecting an end portion of the second penetrating electrode and the one of the first connection pads.