Abstract: An odor treatment device for septic tanks, including an electrolytic oxidation module that has one or multiple electrode sets and processes odor precursors or organic matters that cause odor from organic wastewater and excretion flow inside by an electrolytic oxidation reaction; a supply line through which the excretion is supplied from a septic tank to the electrolytic oxidation module; a circulation line through which the organic wastewater and excretion with the odor precursors and organic matters processed by the electrolytic oxidation module are circulated back to the septic tank; a circulation pump that is disposed in the supply line and continuously circulates the organic wastewater and excretion; a direct current power supply unit that supplies direct current to the electrode sets of the electrolytic oxidation module; and a pump power supply unit that supplies power to the circulation pump.