  With the HDS (High Dispersion Spectrograph) on the Subaru telescope, we
obtained high resolution optical region spectra of three red giant stars (cos
4, cos 82, and cos 347) in the Ursa Minor dwarf spheriodal galaxy. Chemical
abundances in these stars have been analysed for 26 elements including alpha-,
iron-peak, and neutron capture elements. All three stars show low abundances of
alpha-elements (Mg, Si, and Ca) and two stars (cos 82 and cos 347) show high
abundance of Mn compared to Galactic halo stars of similar metallicity. One
star (cos 4) has been confirmed to be very metal deficient ([Fe/H]=-2.7) and
found to show anomalously low abundances of Mn, Cu, and Ba. In another star cos
82 ([Fe/H]=-1.5), we have found large excess of heavy neutron-capture elements
with the general abundance pattern similar to the scaled solar system r-process
abundance curve. These observational results are rather puzzling: low
abundances of alpha-elements and high abundance of Mn seem to sugggest a
significant contribution of SNe Ia at low metallicity, while there is no hint
of s-process (i.e., AGB stars) contribution even at [Fe/H]=-1.5, suggesting a
peculiar nucleosynthetic history of the UMi dSph galaxy.
