PURPOSE: To obtain an ECD low in change with time during high temp. storage, that is, deterioration of electric display amt. after storage by using an org. sulfate for the solvent of an electrolyte between a display member and an opposite electrode.

CONSTITUTION: A display member 3 and an insulator 4 are formed on the transparent electrode 2 of a glass base plate 1, and an opposite electrode 5 is provided with a terminal 10. An org. sulfate, such as dimethyl or diethyl sulfate, dissolving LiClO4 in 0.3M/l is used for a solvent for composing an electrolyte 8. The use of this sulfate reduces deterioration of the display contrast of the element during high temp. storage and it can extremely enhance the reliability of the ECD as an article of commerce.