In this paper, it is shown that application of resistive composite materials depends on its volume electrical resistivity under various conditions. Several conditions require the dependence of volume electrical resistivity on applied voltage to be nonlinear and increasing in strong electric fields. Elastomers with black carbon agglomerated filler are investigated. The value of volume electrical resistivity is controlled by the amount of conductive filler concentration, binder material, type of carbon, and carbon surface processing method. Behavior of voltage- current characteristics in electric fields of various intensity is estimated with a nonlinearity ratio parameter. Several nonlinearity ratio parameters for different composites are obtained, and, in accordance with the results, it is concluded that carbon filled elastomers can be classified as composites with small nonlinearity of voltagecurrent characteristics. It is demonstrated that obtained results can be dependant to specific structure of the agglomerated filler (black carbon). Presented results confirm that small nonlinearity of voltage-current characteristics are caused by the tunnel conductivity of highly-filled elastomers.