The absorption coefficients of cubic LiCl, LiBr, NaCl, NaBr and NaI, and hexagonal LiI are measured in the 5–40 eV region at room and liquid nitrogen temperatures by the use of synchrotron radiation. The purpose is to refine the existing data above 12 eV measured by using spark discharge lamps. Below 12 eV, the obtained spectra agree well with those reported so far except for LiCl. In the 12–30 eV region, spectra are not monotonic but have many weak structures. The weak peaks ascribable to the transitions from the outermost s-levels of the halogen ions are found in the 15–25 eV region.