It has been well established that aluminum (Al) inhibits root tip growth rapidly in acid soil. We report the correlation between Al induced growth inhibition and impaired H⁺-influx in mung bean (Vigna radiata L. cv. Kumsung). The root growth inhibition was dependent on Al concentration (0, 10, 25, 50, 100 μM) and exposure time (12 and 24 h). Using Hematoxylin staining, it was observed that the root damage was occurred preferentially in regions with high Al accumulation. Using the pH indicator, it was shown that the surface pH of root tip was strongly alkalized in the control whereas changed only slightly in the 50 μM Al-treated root. The H⁺-ATPase activity of plasma membrane vesicles was inhibited by 56% in the Al-treated roots compared to control root. Decrease in the amount of the plasma membrane H⁺-ATPase (100 kDa) translation in the plant roots under Al stress was demonstrated by Western blot analysis. These results indicate that the dynamics of H⁺-flux across the root tip play an important role in root growth under Al stress.