Asphalt pavements expose to failure due to various reasons. Moisture failures are the most crucial failures so far. Numerous methods have been carried out to increase asphalt mixtures resistance, one of which is using additives in bitumen or asphalt. This paper intends to determine the effect of amorphous carbon powder on HMAs in order to decrease moisture susceptibility. At the beginning, optimized mixing method of bitumen and carbon powder has evaluated by contact angle test. Carbon powder is utilized in 2 different ways; as additive to bitumen (in weight percentages of 5, 10 and 15) or directly replaced by filler in 25, 50, 75 and 100 percent of mass of filler. Following tests were conducted to study and understand the effect of this powder; proportion of tensile strength in wet and dry conditions based on AASHTO T283, and boiling water test in ASTM D362d. The results of both tests indicate that amorphous carbon powder play an effective role in decreasing the moisture susceptibility of asphalt mixtures. Moreover, replacing this powder by filler shows a much better performance compared to bitumen. Amorphous carbon powder because of its hydrophobicity can be effective to avoid water penetration into asphalt mixture and decrease its moisture susceptibility.