Abstract: In a container which contains an electrochromic solution, a pair of electrodes, namely an indication electrode and a counter-electrode are disposed and an electric circuit is constituted in a manner such that a D.C. pulse is impressed across the electrodes and thereafter the electrodes are shortcircuited to each other. By means of the shortcircuiting, a color indicating substance formed on the indication electrode by the electrochemical reduction reaction or electrochemical oxidation reaction is reversably dissolved from the indication electrode into the solution so as to erase the indication, and therefore contamination of the indication electrode is less and hence a longer life is achieved in comparison with conventional apparatus where such shortcircuiting is not made and simply an inverse pulse is impressed across the electrodes for erasing.