To provide a method and a device that can minimize the usage of an electric double layer capacitor material and evaluate electrochemical charging/discharging characteristics by a simple operation while defining an electrode potential.

A micro-electrode has a concave portion on its end. The concave portion is filled with the particles of an electric double layer capacitor material and electrochemical measurements are performed thereon, so that the usage of a small amount of the electric double layer capacitor material enables quick evaluation with ease. Further, a device is used which comprises the electrode as a reference electrode, a constant-voltage power supply and/or constant-current power supply, a voltage measuring means and/or current measuring means, and a frequency response characteristic evaluating means, so that the usage of a small amount of the electric double layer capacitor material enables quick evaluation with ease.