The PFS Galactic Archaeology Survey is aimed at making constraints on the nature of dark matter in small scales by measuring line-of-sight velocities and chemical compositions of large samples of individual stars. Taking advantage of light gathering power of the 8m Subaru Telescope combined with the wide field-of-view, PFS is capable of systematic surveys of chemodynamical structures among distant stellar populations in the outer disk/halo of our Galaxy, its dwarf satellites and the nearest-neighbor spiral galaxy M31. The unique capability of PFS will allow to make significant progress in our understanding of the structure of dark matter halo as well as the assembly history and the chemical evolution in these galaxies.