Multilayer polarization elements and their applications to polarimetric studies in 20～400 eV region are mainly reviewed.General principle of selecting material combinations to get high linear polarizance multilayers of reflection type is given with practical examples,with periodic or non-periodic layer structures depending on the usage.Transmission type is introduced as linear polarizer and phase shifter.Their applications include polarization diagnosis of laboratory optical systems and synchrotron radiation beamlines of linear and circular polarization,magnetic rotation experiments such as Faraday rotation and magnetic Kerr rotation on magnetic films and multilayers,and ellipsometry to measure optical constants of thin films precisely.Polarization analysis of soft X-ray fluorescence using multilayer-coated grating is also mentioned.Finally this review is summarized with outlook of further developments.