A semiconductor device, includes first, second, and third switching elements. The third switching element comprises first and second terminals. Each of the first and second switching elements comprise a unified ion conductor, a first electrode disposed to contact the ion conductor and supply metal ions thereto, and a second electrode disposed to contact the ion conductor and is less susceptible to ionization than the first electrode. The first electrodes of the first switching element and the second switching element are electrically connected. The first terminal of the third switching element is electrically connected to only the first electrodes which are electrically connected, or the second electrode of the first switching element and the second electrode of the second switching element are electrically connected. The first terminal of the third switching element is electrically connected to only the second electrodes which are electrically connected.