A method for producing a composition having a reverse vesicle structure, the composition comprising the following ingredients,,,, and: a sphingosine represented by formula: wherein R 1 represents a C4 to C30 linear-chain alkyl group which may be substituted by a hydroxyl group, a carbonyl group, or an amino group; Y represents a methylene group, a methine group, or an oxygen atom; each of X 1, X 2, and X 3 represents a hydrogen atom, a hydroxyl group, or an acetoxy group; X 4 represents a hydrogen atom, an acetyl group, or a glyceryl group, or forms an oxo group together with the adjacent oxygen atom; wherein when Y is a methine group, one of X 1 and X 2 is a hydrogen atom, and the other is absent, and when X 4 forms an oxo group, X 3 is absent; each of R 2 and R 3 represents a hydrogen atom, a hydroxyl group, a hydroxymethyl group, or an acetoxymethyl group; a is a number of 2 or 3; each of the "a" groups of Rs represents a hydrogen atom, an amidino group, or a linear-chain alkyl group optionally having a substituent selected from among a hydroxyl group, a hydroxyalkoxy group, an alkoxy group, and an acetoxy group and containing 1 to 8 carbon atoms in total; and the broken line represents an optional unsaturated bond, a C16 to C30 fatty acid, a hydrocarbon oil, an ester oil which is in liquid form at 25°C, and water, wherein the ratio by mass of ingredient to ingredient satisfies the following relationship: 1 ≤ C / D < 1000, and the composition contains a surfactant having a molecular weight of 1,000 or less in an amount of 1 mass% or less, the method comprising the steps of mixing ingredients,,, and, to thereby form an oil phase; heating the oil phase at a temperature at which ingredients,, and are dissolved or higher; adding, to the oil layer, an aqueous phase which contains ingredient and which has been heated to a temperature equivalent to the temperature of the oil phase, to thereby form an emulsion; and cooling the emulsion to room temperature. a sphingosine represented by formula: wherein R 1 represents a C4 to C30 linear-chain alkyl group which may be substituted by a hydroxyl group, a carbonyl group, or an amino group; Y represents a methylene group, a methine group, or an oxygen atom; each of X 1, X 2, and X 3 represents a hydrogen atom, a hydroxyl group, or an acetoxy group; X 4 represents a hydrogen atom, an acetyl group, or a glyceryl group, or forms an oxo group together with the adjacent oxygen atom; wherein when Y is a methine group, one of X 1 and X 2 is a hydrogen atom, and the other is absent, and when X 4 forms an oxo group, X 3 is absent; each of R 2 and R 3 represents a hydrogen atom, a hydroxyl group, a hydroxymethyl group, or an acetoxymethyl group; a is a number of 2 or 3; each of the "a" groups of Rs represents a hydrogen atom, an amidino group, or a linear-chain alkyl group optionally having a substituent selected from among a hydroxyl group, a hydroxyalkoxy group, an alkoxy group, and an acetoxy group and containing 1 to 8 carbon atoms in total; and the broken line represents an optional unsaturated bond, wherein R 1 represents a C4 to C30 linear-chain alkyl group which may be substituted by a hydroxyl group, a carbonyl group, or an amino group; Y represents a methylene group, a methine group, or an oxygen atom; each of X 1, X 2, and X 3 represents a hydrogen atom, a hydroxyl group, or an acetoxy group; X 4 represents a hydrogen atom, an acetyl group, or a glyceryl group, or forms an oxo group together with the adjacent oxygen atom; wherein when Y is a methine group, one of X 1 and X 2 is a hydrogen atom, and the other is absent, and when X 4 forms an oxo group, X 3 is absent; each of R 2 and R 3 represents a hydrogen atom, a hydroxyl group, a hydroxymethyl group, or an acetoxymethyl group; a is a number of 2 or 3; each of the "a" groups of Rs represents a hydrogen atom, an amidino group, or a linear-chain alkyl group optionally having a substituent selected from among a hydroxyl group, a hydroxyalkoxy group, an alkoxy group, and an acetoxy group and containing 1 to 8 carbon atoms in total; and the broken line represents an optional unsaturated bond, a C16 to C30 fatty acid, a hydrocarbon oil, an ester oil which is in liquid form at 25°C, and water,