[en] We have carried out the ¹¹B NMR experiments on single crystalline sample of CeB₂C₂ in order to elucidate the magnetic properties. In the paramagnetic state, the NMR spectrum consists of a sharp peak with satellite lines. The Knight shift, K, decreases upon cooling, which is opposed to the magnetic susceptibility, χ. From the K-χ plot, the hyperfine field at the B sites is estimated to be -1.0 kOe/μ_B, which is suggested to be dominated by the atomic dipolar field. On the other hand, in the AFM phase, the spectrum was broadened and splitted into many resonance peaks by the internal magnetic field at B sites. Also, the temperature dependence of the nuclear spin-lattice relaxation rate, 1/T₁, shows a divergent behavior around T_N, originating from the critical magnetic fluctuation towards a magnetic phase transition. (author)