Abstract: An electrophoretic measurement system for isotachophoresis includes a potential gradient detector, an impedance converter, a voltage to frequency converter, a signal transmission system composed of, for example, electromagnetic wave transmitter means and its receiver spaced therefrom, frequency to voltage converter means, in series connection. This arrangement facilitates insulation of the sensing electrodes of the detector from the ground and prevents a formation of bubbles and deposits on the electrodes, so that the electrophoresis processes are performed under stable condition and high resolution and high sensitivity are obtained. Besides a higher migration current can be used to shorten analysis time.