Electromechanical properties of carbon fiber bundles under tensile deformation were investigated by measuring the strain dependence of electrical resistance. The variation in electrical resistance of carbon/glass hybrid fiber bundles was also measured to understand the effect of glass fibers on their electomechanical behavior. The strength, modulus and breaking strain of samples were dependent on the volume fraction of carbon fiber, and expecially, the absorbed energy largely increased when the volume fraction of carbon fibers was low. The variation in electrical resistance of hybrid fiber bundles was primarily dependent on that of the carbon fibers and even an addition of small amount of carbon fibers could show the electromechanical behavior. However, the strain sensitivity of electrical resistance was much higher for the samples rich in glass fiber. It was ascribed to the variation of contacts between carbon fibers due to the existence of glass fibers. The residual electrical resistance increased with increasing number of cycles of loading/unloading, and with increasing magnitude of elongation. The ratio of irreversible to reversible fractional electrical resistances was found to increase with increase in strain and volume fraction of glass fiber. Consequently, the hybrid carbon fiber bundles containing glass fibers many have a high potential for the electromechanical application such as smart composites.