An electronic device, suitable for achieving a smaller size, includes a semiconductor substrate having a main surface and a back surface opposite to the main surface, a main electronic element arranged on the substrate, and a conducting layer electrically connected to the main electronic element. The substrate is formed with an element arrangement recessed portion that is recessed from the main surface and in which the main electronic element is arranged. The element arrangement recessed portion has a bottom surface facing in the thickness direction, and a side surface inclined with respect to the thickness direction of the substrate. The electronic device includes an auxiliary electronic element formed on the side surface of the element arrangement recessed portion.