There is provided a method for handling an aqueous solution containing a water-soluble substance that changes into a water-insoluble substance over time, including a step of bringing the aqueous solution to be treated containing the water-soluble substance that changes into the water-insoluble substance over time into contact with a water-insoluble organic solvent, and extracting the water-soluble substance into the water-insoluble organic solvent. Preferably, the water-soluble substance is alkylbenzene hydroperoxide, and the water-insoluble substance is alkylbenzene hydroperoxide-derived alcohol. Preferably, the aqueous solution to be treated is an alkaline aqueous phase separated in a water-washing step in a process of manufacturing the alkylbenzene hydroperoxide that has an alkali extraction step, the water-washing step, an oxidation step, and a reaction solution separation step.