A semiconductor device and a manufacturing method thereof are provided with downsizing and densification achieved by reducing the thickness of the semiconductor device without increase in area. Terminal electrodes are arranged, in plan view, outside a region where semiconductor chips are arranged. A lower semiconductor chip is placed to overlap in the range of height with the terminal electrodes, an upper semiconductor chip is placed above the lower semiconductor chip, a wire connects the upper and lower semiconductor chips to the terminal electrodes, and an encapsulating resin encapsulates the upper and lower semiconductor chips and wire. The encapsulating resin has its bottom surface coplanar with the bottom surface of the terminal electrodes.