An X-ray analysis system , comprising: an X-ray spectrometer ; and a vapor phase decomposition apparatus , wherein the X-ray spectrometer includes: an X-ray source configured to irradiate a measurement sample having a thin film present on a surface of the measurement sample with primary X-rays; a detector configured to measure an intensity of reflected X-rays obtained when the primary X-rays are reflected by the surface or an interface of the measurement sample , or an intensity of fluorescent X-rays generated by the primary X-rays; and a calculation unit configured to calculate a film thickness or a coating mass of the thin film based on the intensity of the reflected X-rays or the fluorescent X-rays, and further configured to calculate a density of the thin film, and wherein the vapor phase decomposition apparatus includes: a vapor phase decomposition portion configured to perform vapor phase decomposition on the thin film; and a control portion configured to determine a vapor phase decomposition time based on the film thickness or the coating mass calculated by the calculation unit , and further configured to correct, based on the density, the determined vapor phase decomposition time. an X-ray spectrometer ; and a vapor phase decomposition apparatus , wherein the X-ray spectrometer includes: an X-ray source configured to irradiate a measurement sample having a thin film present on a surface of the measurement sample with primary X-rays; a detector configured to measure an intensity of reflected X-rays obtained when the primary X-rays are reflected by the surface or an interface of the measurement sample , or an intensity of fluorescent X-rays generated by the primary X-rays; and a calculation unit configured to calculate a film thickness or a coating mass of the thin film based on the intensity of the reflected X-rays or the fluorescent X-rays, and further configured to calculate a density of the thin film, and an X-ray source configured to irradiate a measurement sample having a thin film present on a surface of the measurement sample with primary X-rays; a detector configured to measure an intensity of reflected X-rays obtained when the primary X-rays are reflected by the surface or an interface of the measurement sample , or an intensity of fluorescent X-rays generated by the primary X-rays; and a calculation unit configured to calculate a film thickness or a coating mass of the thin film based on the intensity of the reflected X-rays or the fluorescent X-rays, and further configured to calculate a density of the thin film, and wherein the vapor phase decomposition apparatus includes: a vapor phase decomposition portion configured to perform vapor phase decomposition on the thin film; and a control portion configured to determine a vapor phase decomposition time based on the film thickness or the coating mass calculated by the calculation unit , and further configured to correct, based on the density, the determined vapor phase decomposition time. a vapor phase decomposition portion configured to perform vapor phase decomposition on the thin film; and a control portion configured to determine a vapor phase decomposition time based on the film thickness or the coating mass calculated by the calculation unit , and further configured to correct, based on the density, the determined vapor phase decomposition time. <EOS>