An object is to provide an immunochromatographic analysis method capable of shortening the developing time without decreasing the detection sensitivity, and also capable of reducing the return of the liquid of a developed component, and a method for detecting a detection target contained in an analyte using an immunochromatographic analysis device including an absorption part composed of glass fiber, wherein the analyte and a labeling substance are developed in a chromatography medium part as a mobile phase in the presence of a nonionic surfactant, and the detection target is detected in a detection part is provided.