The detailed theoretical studies for TCNQ/TCNQ(-.) salts, which possess ferromagnetic hysteresis at relative high temperature, were carried out. The calculations based on ab initio molecular orbital (MO) and density functional (DFT) theories were carried out to evaluate the intermolecular effective exchange integrals and transfer integrals. In addition, we employed the "hybrid DFT method" based on instability of chemical bonds and successfully studied their spin densities. From the results it was found the remarkable singlet dimer structure is dominant. In addition, quasi-one-dimensional structure was found because of nonzero charge transfer.