195Pt-,¹³⁹La- and ¹¹B-NMR have been investigated in quaternary RM₂B₂C (R=Y,La,Th and M=Ni,Pd,Pt). The electric quadrupole frequency of ¹³⁹La changes more than 5 times in magnitude from M=Ni to Pt, indicating that the hybridization of La-5d and d-electrons of M-element changes largely. The analysis of ¹¹B and ¹³⁹La spectra shows also the large change of the magnetic anisotropy with R and M element, i.e., χ_c > χ_ab in LaNi₂B₂C, but χ_c < χ_ab in YNi₂B₂C. The data of T₁T and K of ¹⁹⁵Pt and ¹¹B are consistent with the band effects and with no evidence of strong antiferromagnetic correlation effects.