An analysis method having: a sample preparation step of preparing a measurement sample by mixing a measurement object containing pyrroloquinoline quinone or a salt thereof with glycine so that the pyrroloquinoline quinone or the salt thereof reacts with the glycine to produce imidazopyrroloquinoline or a salt thereof; and a quantitative analysis step of determining quantitatively the amount of the pyrroloquinoline quinone and the salt thereof contained in the measurement object, based on a chromatogram of the imidazopyrroloquinoline or the salt thereof contained in the measurement sample obtained by chromatography.