The effects of carbon blacks mixed to rubber compounds. on various physical properties and adhesion between brass-coated wire and rubber compound were examined in this study. Four types of carbon black with various iodine numbers and dibutylphthalate absorption numbers were used. The maximum torque, hardness, and modulus increased as the mixing amount of carbon black increased in the range of 20∼80 phr. The significance of the types of carbon black to the improvement of strength was not observed. Tensile strength and tear strength were increased by adding carbon black, but decreased at 80 phr of loading level after showing maximum values for the carbon black with relatively larger iodine number. The adhesion strength evaluating by the pullout force of TCAT (Tire Cord Adhesion Test) sample was increased with increasing the amount of carbon black, but the degree of rubber coverage was almost constant as 90%. The plot of 100% modulus of rubber compound versus pullout force showed a linear relationship, indicating that the enhancement of adhesion might be caused by the fatigue resistance of rubber compound improved by carbon black.