  We present the results of deep near-infrared imaging observations of the
z=3.1 proto-cluster region in the SSA22a field taken by MOIRCS mounted on the
Subaru Telescope. We observed a 21.7 arcmin^2 field to the depths of J=24.5,
H=24.3, and K=23.9 (5 sigma). We examine the distribution of the K-selected
galaxies at z~3 by using the simple color cut for distant red galaxies (DRGs)
as well as the photometric-redshift selection technique. The marginal density
excess of DRGs and the photo-z selected objects are found around the two most
luminous Ly alpha blobs (LABs). We investigate the correlation between the
K-selected objects and the LABs, and find that several galaxies with stellar
mass M_* = 10^9-10^11 M_solar exist in vicinity of LABs, especially around the
two most luminous ones. We also find that 7 of the 8 LABs in the field have
plausible K_s-band counterparts and the sum of the stellar mass possibly
associated with LABs correlates with the luminosity and surface brightness of
them, which implies that the origin of Ly alpha emission may be closely
correlated with their stellar mass or their previous star formation phenomena.
