Grip performance and braking distance of a tire strongly depend on the frictional characteristics between the tread (the part which touches to the road surface) rubber and the road surface. To meet the complex needs of a tire, a polymer blend is commonly used and the fillers in the polymer blend may have a great influence on tire properties. In this paper, a bias dispersion state of carbon black (CB) in polymer blended rubber composites consisting of styrene butadiene rubber (SBR) and natural rubber (NR) was observed by scanning probe microscope (SPM). It was indicated that the SBR/CB interaction in rubber composite was stronger than that of the NR/CB interaction by measuring tensile strength in NR/SBR blended rubber composites. It was found that island patterns of SBR phase were formed in the polymer and more carbon blacks were segregated in SBR phase than in NR phase. Then a method to predict the distribution ratio of CB in SBR phase was proposed according to characteristic behavior of storage modulus in dynamic viscoelasticity. And the concentration of CB in SBR phase was estimated to be about twice as large as that in NR phase.