A transmission X-ray analyzer (1) for detecting a transmission X-ray image of a sample (100) that is continuous in a band shape includes: a TDI sensor (14); an X-ray source (12) arranged opposed to a TDI sensor; a pair of support rollers (31, 32) arranged away from the TDI sensor between the TDI sensor and the X-ray source, the pair of support rollers being configured to transport the sample to a detection position of the TDI sensor while keeping a constant interval between the TDI sensor and the sample; and a pair of outside rollers (51, 52) arranged respectively on an outer side of the pair of support rollers in a transportation direction (L). One of the pair of support rollers and one of the pair of outside rollers are arranged at different positions as to apply a tension to the sample between the pair of support rollers.