A semiconductor apparatus (10) includes: a layered structure (100) that includes double junction structures that have a first junction (151, 153) where a wide-bandgap layer (102, 104) and a narrow-bandgap layer (101, 103, 105) are layered on each other and a second junction (152, 154) where a narrow-bandgap layer (101, 103, 105) and a wide-bandgap layer (102, 104) are layered on each other, and electrode semiconductor layers (110, 120) are joined to each layer of the layered structure. Each double junction structure includes a pair of a first region (131, 133) that has negative fixed charge and a second region (132, 134) that has positive fixed charge. The first region is closer to the first junction than to a center of the wide-bandgap layer. The second region is closer to the second junction than to the center of the wide-bandgap layer. A 2DEG or a 2DHG is formed at each junction. The semiconductor apparatus functions as an electric energy storage device such as a capacitor.