Abstract: In a waiting period in which a transmission state of an electrodeposition element is held to be a predetermined transmission state such as a full-transmission state, based on a frequency, a duty ratio, a first voltage and a second voltage set in advance, a transmittance holding pulse generating section generates a pattern of a transmittance holding pulse having a cycle corresponding to the frequency and continuously outputs the pattern of the transmittance holding pulse to the electrodeposition element. In a light reduction period in which the transmission state of the electrodeposition element is held to be a light-reduced state (transmittance is lowered), the deposition start voltage generating section applies a third voltage, which is a preset deposition start voltage, to the electrodeposition element. Consequently, metal ions are easily deposited, enabling increasing a speed of dispersion of the metal ions.