  We discuss the properties of galaxies around the radio galaxy 3C 324 at z=1.2
based on BVRIK' multi-band imaging data. We have applied a photometric-redshift
technique to objects in the 3C 324 field, and identified 35 objects as
plausible cluster members. We have found that red and luminous members are
concentrated in a small region enclosed by a circle of 40" radius (0.33 Mpc at
z=1.2 for \Omega_0=0.3, \lambda_0=0.7, H_0=70km/s/Mpc cosmology) from the 3C
324 galaxy. The 3C 324 cluster is probably much more compact in size compared
with the local clusters. We constructed a K'-band luminosity function of the
cluster members and fit a Schechter function, and found the characteristic
magnitude to be K*_{AB}=20.2+-0.6. This value is consistent with the
extrapolation of the pure passive evolution seen for z<1 clusters. We have
identified eight bright galaxies which form a red color-magnitude sequence. The
slope of the sequence is consistent with the passive evolution model down to
K'_{AB}<22; we also found that there is no clear age variation in these bright
red galaxies. However, seven out of these eight galaxies exhibit a significant
excess in the rest UV light with respect to the passive evolution model. This
may suggest that the massive early-type galaxies in this high-redshift cluster
are still forming stars to some extent. We have confirmed a truncation of the
color-magnitude sequence at K'_{AB}\sim22; faint passively-evolving galaxies
may not yet be present in this cluster at z\sim1.2. The overall color
distribution of the cluster members, selected by the photometric redshift
technique, is found to be very broad. We derived the fraction of blue galaxies
in this cluster following a
