A semiconductor device is designed such that a semiconductor sensor chip having a diaphragm for detecting pressure variations based on the displacement thereof is fixed onto the upper surface of a substrate having a rectangular shape, which is covered with a cover member so as to form a hollow space embracing the semiconductor sensor chip between the substrate and the cover member. Herein, the substrate is sealed with a molded resin such that chip connection leads packaging leads are partially exposed externally of the molded resin; the chip connection leads are electrically connected to the semiconductor sensor chip and are disposed in line along one side of the semiconductor sensor chip; and the packaging leads are positioned opposite the chip connection leads by way of the semiconductor sensor chip. Thus, it is possible to downsize the semiconductor device without substantially changing the size of the semiconductor sensor chip.