A method for manufacturing a hydrocarbon oil, comprising: a first step wherein a feedstock oil containing an oxygen-containing organic compound and a water-insoluble chlorine-containing compound is brought into contact with a hydrogenation catalyst comprising a support containing a porous inorganic oxide and one or more metals selected from Group VIA and Group VIII of the periodic table supported on the support in the presence of hydrogen to generate a hydrocarbon oil and water in a vapor state by the hydrodeoxygenation of an oxygen-containing organic compound and convert the water-insoluble chlorine-containing compound into a water-soluble chlorine-containing compound; a second step wherein the water in the reaction product of the first step is maintained in a vapor state and the reaction product of the first step is brought into contact with a nitrogen-containing Brønsted base compound which has a boiling point at normal pressure of 100°C or less and is water-soluble to obtain a product to be treated; and a third step wherein the product to be treated is cooled to a temperature not higher than the temperature at which water in a vapor state is liquefied to form an aqueous phase containing a water-soluble chlorine-containing compound and a nitrogen-containing Bronsted base compound and then separate the aqueous phase from an oil to be treated to obtain a product oil containing a hydrocarbon oil.