This electrochemical device comprises: first and second substrates facing each other and having electrodes on the facing surfaces thereof; an electrodeposition material which is sandwiched between thefirst and second substrates and contains Ag; a mediator; a supporting electrolyte; and a solvent. The electrochemical device also has a transparent electrolyte solution having an absorbance of 0.1 orless in the 400-800 nm wavelength visible light region, and has a cell thickness of 1-1000 Mum.