The Milky Way dwarf spheroidal (dSph) galaxies are excellent laboratories to shed light on fundamental properties of dark matter.
Especially, the dSphs are the promising targets for the dark matter indirect searches for particle dark matter.
To place robust constraints on candidate dark matter particles, understanding dark matter distributions of these systems is of substantial importance.
However, there are various non-negligible systematic uncertainties on the estimate of dark matter distributions in these galaxies.
In particular, the effects of non-sphericity of dark halos and the contamination stars are significant and unavoidable uncertainties.
Therefore, it is necessary to address development of dynamical models considering the effects of these systematic uncertainties.
In this talk, I will introduce our new dynamical models taking into account these uncertainties and show the results of the estimate of dark halo profiles in the dSphs.
Also, I will present the future prospects for studying dark matter in the dSphs using Subaru Prime Focus Spectrograph which is a massively-multiplexed fiber-fed spectrograph and thus enables us to hunt a huge number of dSph's kinematic data.