An electroanalytical method which can detect and determine a substance in a short time, with stability and simply is provided, which method comprisesproviding an electrolytic cell provided with a working electrode chamber and a counter electrode chamber adjacent thereto by the medium of a separator electrolyzing a sample to be determined, by feeding it to a working electrode contained in the working electrode chamber and consisting of an electroconductive porous body impregnated with an electrolyte in a non-flowing state; and measuring at least one of the electric voltage, electric current and electrical quantity in the working electrode, to determine the substance in the sample.