A deionization apparatus comprising: electrodes (11, 12) to which ions contained in a fluid are absorbed, the electrodes (11, 12) including a positive electrode and a negative electrode; a piezoelectric element to separate the ions absorbed by the electrodes (11, 12) by vibration, with (i) the piezoelectric element being disposed between the positive electrode and the negative electrode and the piezoelectric element having a porous structure to allow passage of the fluid; or (ii) the electrodes (11, 12) including a current collector and a porous carbon electrode (11, 12), and the piezoelectric element being disposed between the current collector and the porous carbon electrode (11, 12); or (iii) the electrodes (11, 12) including a current collector and a porous carbon electrode (11, 12), and the current collector being disposed between the piezoelectric element and the porous carbon electrode (11, 12); the deionization apparatus further comprising: a generator to apply a sine wave signal to the electrodes (11, 12) so as to generate the vibration of the piezoelectric element; a power amplifier to amplify the sine wave signal to a predetermined voltage to operate the piezoelectric element; a DC power source to apply a DC voltage to the electrodes (11, 12) in order to absorb the ions of the fluid; and a capacitor (C1, C2) disposed between the DC power source and the power amplifier so as not to apply the DC voltage to the power amplifier. electrodes (11, 12) to which ions contained in a fluid are absorbed, the electrodes (11, 12) including a positive electrode and a negative electrode; a piezoelectric element to separate the ions absorbed by the electrodes (11, 12) by vibration, with (i) the piezoelectric element being disposed between the positive electrode and the negative electrode and the piezoelectric element having a porous structure to allow passage of the fluid; or (ii) the electrodes (11, 12) including a current collector and a porous carbon electrode (11, 12), and the piezoelectric element being disposed between the current collector and the porous carbon electrode (11, 12); or (iii) the electrodes (11, 12) including a current collector and a porous carbon electrode (11, 12), and the current collector being disposed between the piezoelectric element and the porous carbon electrode (11, 12); (i) the piezoelectric element being disposed between the positive electrode and the negative electrode and the piezoelectric element having a porous structure to allow passage of the fluid; or (ii) the electrodes (11, 12) including a current collector and a porous carbon electrode (11, 12), and the piezoelectric element being disposed between the current collector and the porous carbon electrode (11, 12); or (iii) the electrodes (11, 12) including a current collector and a porous carbon electrode (11, 12), and the current collector being disposed between the piezoelectric element and the porous carbon electrode (11, 12); the deionization apparatus further comprising: a generator to apply a sine wave signal to the electrodes (11, 12) so as to generate the vibration of the piezoelectric element; a power amplifier to amplify the sine wave signal to a predetermined voltage to operate the piezoelectric element; a DC power source to apply a DC voltage to the electrodes (11, 12) in order to absorb the ions of the fluid; and a capacitor (C1, C2) disposed between the DC power source and the power amplifier so as not to apply the DC voltage to the power amplifier. a generator to apply a sine wave signal to the electrodes (11, 12) so as to generate the vibration of the piezoelectric element; a power amplifier to amplify the sine wave signal to a predetermined voltage to operate the piezoelectric element; a DC power source to apply a DC voltage to the electrodes (11, 12) in order to absorb the ions of the fluid; and a capacitor (C1, C2) disposed between the DC power source and the power amplifier so as not to apply the DC voltage to the power amplifier.