Abstract: A novel fluorescent group-containing carbodiimide compound having at least one group selected from a carboxyl group, a sulfo group, a phosphono group and a phospho group which have substitution of an alkali metal, an alkaline earth metal or a basic group containing a nitrogen or phosphorus atom, which is prepared by using a novel fluorescent group-containing carbodiimide compound precursor having a halogen atom or a sulfonic acid group; and a method for detecting a nucleic acid by hybridization utilizing a nucleic acid labeled with a labeling substance, which utilizes the fluorescent group-containing carbodiimide compound as the labeling substance.