PURPOSE: To accurately carry out the measurement of electrochemical polarization characteristics, by a method wherein a light path is provided between two electrodes attached to an electrode holder so as to pass the connecting line of said electrodes and a short circuit current is measured to detect the amount of a corrosive product.

CONSTITUTION: A light path is provided between two electrodes 4 attached to an electrode holder 3 so as to pass the connecting line of said electrodes 4 and generated from a light source 7 provided to the center of the electrode holder 3 and passed between the electrodes 4 to detect quantity of light thereof by a detector attached to the insulating support plate 8 positioned at the leading end of the electrodes 4. By this apparatus constituted as mentioned above, a short circuit current detected by a solar cell is practically measured to make it possible to detect the amount of a corrosive product accumulated on the electrodes and measurement can be accurately carried out.