An application of quantum chemical modeling allowed us to investigate a substituent effect on a sigma and pi electron structure of a ring and the nitro group in a series of meta- and para-X-substituted nitrobenzene derivatives (X = NMe2, NHMe, NH2, OH, OMe, Me, H, F, Cl, CF3, CN, CHO, COMe, CONH2, COOH, NO2, and NO). The obtained pEDA and sEDA parameters (the pi- and sigma-electron structure characteristics of a given planar fragment of the system obtained by the summation of pi- and sigma-orbital occupancies, respectively) of the NO2 group and the benzene ring allowed us to reveal the impact of the substituents on their mutual relations as well as to analyze them from the viewpoint of substituent characteristics. The decisive factor for dependence of pEDA on sEDA of the ring is electronegativity of the atom linking the substituent with the ring; in subgroups an increase of sEDA is associated with a decrease of pEDA. The obtained mutual relation between pEDA(NO2) and pEDA(ring) characteristics documents strong resonance interactions for electron-donating substituents in the para position. The observed substituent effect on the sigma-electron structure of the nitro group, sEDA(NO2), is significantly greater (similar to 1.6 times) for meta derivatives than for the para ones.