PURPOSE: To greatly enhance an oxidation treatment efficiency of organic- containing waste water.

CONSTITUTION: This wet type oxidation treatment method treats the organic- containing waste water incorporating large quantities of organic acid salts by adding sulfate ions and/or chlorine ions corresponding to 0.5-25 equivalents of the alkali metal quantities and/or alkaline earth metal quantities and the alkali metal ion quantities and/or alkaline earth metal ion quantities not neutralized in the waste water contained in the organic acid salts, and the wet type oxidation treatment is conducted.