アブストラクト：
We report the environmental effects on the Mass-Metallicity relation in the distant universe at z~1.5, based on our LBT/LUCI and Subaru/MOIRCS spectroscopic observations in the field around a radio galaxy, 4C65.22 at z=1.52. Firstly we measured the redshifts of 44 galaxies in this field and confirmed that these galaxies are really concentrated around z=1.52. We then investigated their gas-phase metallicity with multi emission lines. We find that, in this rich cluster environment at z=1.52, low-mass galaxies (with $M_*<10^{10.5}M_\odot$) tend to have higher metallicity than those in the field environment.