PURPOSE: To reduce the thickness of an electrochromic display device (ECD) and to simplify the manufacture by forming the opposite electrode of the device with paste prepared by mixing activated carbon or carbon black with a water- soluble high-molecular cellulose binder.

CONSTITUTION: An aqueous soln. of a mixture consisting of activated carbon or carbon black and a water-soluble high-molecular cellulose binder such as CMC, Na salt thereof or ethylcellulose in 6:1wt. ratio is applied to the surface of an electrode film 11 formed on the inside of a background substrate 10 for an ECD, and the soln. is dried at 100°C for about 30min to form an opposite electrode 6. After setting a white ceramic plate 5, a display electrode substrate 1 provided with a transparent electrode 2 and a display electrode 3 is joined to the substrate 10 with a spacer 12 in-between. An electrolytic soln. 9 is then injected, and the cell is sealed to finish an ECD. The opposite electrode 6 is formed in a small thickness such as about 0.1W0.2mm, is porous, and has a high responding speed to an applied voltage, so a thin simplified ECD is obtd.