NOVELTY - Preparation of a water-insoluble liquefied fuel oil (I) containing a hydrocarbon comprises: subjecting a mixture that contains biomass (7) containing lignocellulose, an organic solvent, and water to liquefaction; simultaneously with or after liquefaction, causing a mixture (II) of the liquefied fuel oil containing the solvent and an aqueous phase containing a water-soluble organic substance to come into contact with a dehydration catalyst under pressure and then subjecting the resultant to dehydration; and separating (I) from the mixture.    USE - The method is useful for preparing a water-insoluble liquefied fuel oil (I) containing a hydrocarbon, which is useful as a fuel oil for automobiles or motorbikes, boilers and power generators.    ADVANTAGE - The method provides high yield of (I) and the degeneration of the solvent to be used for liquefaction is low. (I) has a zero carbon dioxide emission count, thus solving global environmental problems such as global warming.    DETAILED DESCRIPTION - Preparation of a water-insoluble liquefied fuel oil (I) containing a hydrocarbon comprises: subjecting a mixture that contains biomass (7) containing lignocellulose, an organic solvent, and water to liquefaction; simultaneously with or after liquefaction, causing a mixture (II) of the liquefied fuel oil that contains the organic solvent and an aqueous phase that contains a water-soluble organic substance to come into contact with a dehydration catalyst under pressure and then subjecting the resultant to dehydration, or causing (II) to come into contact with hydrogen in the presence of a hydrogenation catalyst under pressure, and then subjecting the resultant to hydrogenation; and separating (I) from the mixture after dehydration or hydrogenation.    DESCRIPTION OF DRAWING(S) - The diagram shows an apparatus for the method for producing a water-insoluble liquefied fuel oil containing hydrocarbon.    Storage tank (1)    Solvent transfer pump (4)    Solvent heater (5)    Biomass liquefaction reactor (6)    Biomass. (7)