PURPOSE: To improve memory characteristic using electrodes consisting of transition metallic oxide films by adding phosphoric acid in an electrolyte using propylene carbonate as a solvent.

CONSTITUTION: Films of transition metallic oxides such as WO3, MoO3, V2O5 or the like are used as electrochromic display materials and propylene carbonate is used as a solvent for the electrolyte. Phosphoric acid is added at ≥ 0.04mol/l concn. into the electrolyte of such electrochemical cell, for example, the electrolyte prepd. by dissolving lithium perchlorate at 1 mol/l concn. into propylene carbonate. Transparent electrodes 1 are patterned on, for example, upper glass 4, and a WO3 film 2 is vapor-deposited thereon. An insulation film 3 is coated on the parts other than the WO3 film. Recessed glass 5 provided with a sputtered film 6 of Cr-Au thereon is disposed on the lower side, and the upper and lower glasses 4, 5 are sealed by epoxy resin. The above-mentioned electrolyte 7 is injected therein, whereby the panel for digital timepieces is manufactured.