Provided is a method for electrolyzing alkaline water whereby degradation of cathode and anode performance can be minimized even when operation is carried out in conditions of frequent repetition of starting and stopping and in conditions of considerably fluctuating output. The present invention provides a method for electrolyzing alkaline water in which intermittent operation is repeated, the method for electrolyzing alkaline water being characterized in comprising: an electrolysis step for housing an electrolyte (16) in a circulation tank (5), feeding the electrolyte (16) in the circulationtank (5) to an anode chamber (2) and a cathode chamber (3), returning the electrolyte generated in the cathode chamber (3) and the electrolyte generated in the anode chamber (2) to the circulation tank (5), mixing the electrolyte in the circulation tank (5), and thereafter electrolyzing alkaline water while the mixed electrolyte is recirculated to the anode chamber (2) and the cathode chamber (3);and a step for adding a catalyst-activating material composed of a soluble metal salt to the electrolyte (16) prior to the start of the electrolysis step, the metal in the catalyst-activating material being plated on the cathode surface in the electrolysis step.