Monte Carlo simulation and molecular orbital calculation were carried out for the H2NO radical in H2O and CH3OH, and the solvent effects on the molecular structure and the electronic structure of H2NO were elucidated. In vacuo, the NO bond bends from the molecular plane. The barrier of inversion of the NO bond, which is 0.86 kcal/mol in the gas phase, decreases in solution and becomes very small in H2O. ESR parameters of H2NO strongly depend on the molecular structure, and the hyperfine coupling constants, which agree well with experiment, were obtained by including both the molecular vibrational effect of the NO bond and the solvent effect which was represented by point charge approximation for the solvent configurations generated by the MC simulation.