My research interest is dark halo structures of dwarf galaxies in the Local Group. These galaxies are ideal sites for studying the fundamental properties of dark matter, because such satellites are the most dark-matter-dominated systems. In order to gain useful insight into dark halo structures on small-mass scales, I am studying the stellar dynamics of their member stars, mainly by using our constructed mass models. Using a number of the kinematical data measured by Prime Focus Spectrograph attached to the Subaru Telescope, I hope to obtain stronger limits on dark halo structures and their dynamical evolutions.