Molecular geometries of benzene, toluene, aniline, N-methylaniline, benzylamine and cyclopentadienyl anion were optimized at the B3L YP/6-311 ++G(d,p) level of theory. The aromaticity of all structures was evaluated by using geometric, energetic and magnetic criteria. This study shows that all these examined compounds are aromatic, and the prediction on magnitude of aromaticity can not be determined by only any single criterion that has to be combined by many differrent factors. The more criteria are used, the more reasonable results are obtained. It is remarkable that benzylamine is an aromatic amine and its aromaticity is even more than that of aniline and N-methylaniline. Furthermore, the obtained results also indicate that benzene is a perfect model compound of aromaticity since the substituents of the H atom in benzene by different groups make its conjugated system stability decreased. And finally, according to our results it is better for the N1CS22 than for the NICSiso in estimating the aromaticity of examined compounds.