d no trend with metallicity in the range of $-1.2$ [${<}\atop{\sim}$]{}\[Fe/H\] [${<}\atop{\sim}$]{}$-0.3$. Prochaska et al. (2000) also postulated that a more careful, extensive stellar abundance analysis of S in metal-poor stars is warranted since S is one of important elements in quasar absorption-line studies.

Very recently, Israelian & Rebolo (2001) analyzed the S abundances in six metal-poor stars with metallicities in the range of $-3 <$ \[Fe/H\] $<-0.2$ using observational data of [S [i]{} ]{}lines at 8694 Å. Their results indicate a monotonic increase of \[S/Fe\] as \[Fe/H\] decreases, reaching \[S/Fe\]$ \sim 0.7$ – $0.8$ below \[Fe/H\] $= -2$.

Takeda et al. (2002; hereafter Paper I) also very recently reported the abundance analysis of S for very metal-poor giants with \[Fe/H\] [${<}\atop{\sim}$]{}$-1.5$ observed with the High Resolution Echelle Spectrometer (HIRES; Vogt 1994) of the 10 m Keck I telescope as a byproduct in the oxygen abundance study. It is suggested that \[S/Fe\] increases linearly with decreasing \[Fe/H\], which is just the same trend as found in Israelian & Rebolo (2001), and this behavior resembles that of O. However, Paper I’s results of S are yet preliminary and should be superseded with those of this study.

In this paper, in order to explore the behavior of S in the metallicity range of $-3$ [${<}\atop{\sim}$]{}\[Fe/H\] [${<}\atop{\sim}$]{}$+0.5$, we carried out extensive LTE abundance analyses of S for the six samples of very metal-poor stars in Paper I observed with the Keck I HIRES (hereafter, the HIRES sample) and of metal-poor dwarfs observed at the Okayama Astrophysical Observatory (hereafter, the OAO sample). We also re-analyze the data of dwarfs observed by Clegg et al. (1981) and Fran[ç]{}ois (1987, 1988) based on our system of analysis to eliminate the systematic differences between our and the previous analyses. We further perform the non-LTE (NLTE) abundance analysis for all these sample stars to examine how the NLTE abundances of S behave and how the NLTE a