Although a lot of charging behavior for toner and carrier has been reported, little work on toner-toner interaction force has been done in two component development system. The purpose of the present research was to investigate the toner-toner interaction force with two kind of toners which had opposite polarity each other and equivalent charge-to-mass ratio against a certain carrier.It was shown that by mixing the carrier and different mixing ratio of these two kinds of toners, the developer flow was affected by the mixing ratio. Additionally, these toners showed visible agglomerations by electrostatic attractive force when they mixed, and the interaction force was also investigated quantitatively as toner flow ability and cohesiveness by changing the ratio of the two toner mixes.Charge distribution spectrographs of those developers were also measured with E-SPART analyzer, and as the results, such blending of positive and negative polarity toners in the ratio of one to one showed a single peak in the vicinity of zero charge instead of the bi-model charge distribution split into plus and negative region. Thus, charge distribution of those developers has been incorporated in toner-toner interaction.