I would like to review AGN related researches with Subaru, focusing
efforts toward complete understanding of accretion history in the
universe and its relation to the galaxy evolution. Combination of 
hard X-ray surveys and optical follow-up observations is an efficient 
way to trace the accretion history in the universe, i.e. to pick up 
AGNs with various intrinsic absorption in the wide luminosity and 
redshift ranges. After the launches of Chandra and XMM-Newton, many
hard X-ray surveys and optical follow-up observations have been
conducted and they revealed large number of obscured AGNs. However,
significant fraction of the X-ray sources have a faint optical
counterpart, and understanding of the optically-faint population is
still limited. We examined the nature of the optically-faint X-ray
sources using deep and wide optical imaging data taken with Suprime-cam,
deep optical spectroscopic data with FOCAS, and NIR spectroscopic data
by MOIRCS. Their natures are consistent with obscured AGNs at z=1-3.
The redshift distribution of the optically-faint AGNs indicates that
there are large number of obscured AGNs in the redshift range.
The estimated stellar mass of the obscured AGNs ranges 10^10-12
solar masses and rather constant for AGNs with wide redshift and
luminosity range. The relation between the host galaxies of the X-ray
AGNs and non-active galaxies will be discussed by locating the 
host galaxies among the field galaxies in the same field.