Provided is a method for measuring soluble LR11 in a biospecimen such as blood serum, without requiring isolation of the soluble LR11 therefrom, by using a simple and accurate immunological means. A method for immunologically measuring soluble LR11 in a biospecimen, the method for immunologically measuring the soluble LR11 being characterized in that the specimen is treated using at least one type of surfactant selected from a sulfobetaine amphoteric surfactant and an amidosulfobetaine amphoteric surfactant.
