To provide an electrochemical water treatment method cable of sterilizing with high efficiency microorganisms existing in every kind of water such as drinking water, industrial water or the like by performing the treatment stably over a long period.

In the water treatment method for supplying a current to an electrolytic cell wherein a porous carbon electrode is mounted between power supply terminal electrodes to polarize the porous carbon electrode and supplying water to be treated containing microorganisms to the electrolytic cell to sterilize microorganisms electrochemically, the porous carbon electrode is periodically taken out of the electrolytic cell to be subjected to heat treatment and subsequently washed with water to remove the residue bonded to the porous carbon electrode. The heat treatment is preferably performed in air for one hr or more at 180-400°C or performed in an inert atmosphere for one hr or more at 180-1,200°C.