Abstract: A method for detecting or quantifying an analyte, using a test strip for lateral flow type chromatography which contains a membrane and a detection part on which a capturing ligand that is to specifically bind to the analyte has been fixed on the membrane, includes: bringing an analyte contained in a sample into contact with a labeled ligand labeled with a phosphor that is to be excited by light having a wavelength from 600 nm to 800 nm to generate fluorescence, bringing a complex containing the analyte and the labeled ligand into contact with a capturing ligand at the detection part, and irradiating on the test strip light having a wavelength from 600 nm to 800 nm as an excitation light for the phosphor contained in the complex to generate fluorescence from the phosphor, and measuring a fluorescence intensity of the fluorescence.