A switching device includes a first switching element having a snap-back behavior characteristic, an output voltage of the first switching element decreasing when an input current increases from a turn-on threshold current of the first switching element. The switching device further includes a second switching element having a continuous-resistance behavior characteristic, an output voltage of the second switching element increasing when the input current increases from a turn-on threshold current of the second switching element. The turn-on threshold current of the first switching element is lower than the turn-on threshold current of the second switching element.