To provide a method and a device for liquid treatment which suppress not only the rise of the temperature of a liquid to be treated but also the consumption of energy, by reducing a leakage current to the liquid as much as possible and controlling a route of flow of a minute leakage current which cannot be stopped, to suppress the occurrence of a module loss due to the leakage current, when pulselike power is supplied between electrode pairs to reform the liquid existing between electrode pairs.

In a method for liquid treatment in which the pulselike power is supplied between electrode pairs to reform the liquid to be treated which exists between electrode pairs, each electrode pair consists of an electrode electrically exposed to the liquid and an electrode which is so protected that it may not be electrically exposed to the liquid, and at least two electrode pairs are included, and the electrode electrically exposed to the liquid of one of two electrode pairs arbitrarily selected from these electrode pairs and the electrode, which is so protected that it may not be electrically exposed to the liquid, of the other electrode pair are mutually electrically connected to perform operation.