Drought and salt are major abiotic stresses that adversely affect crop productivity. Thus identification of factors that confer resistance to these stresses would pave a way to increasing agricultural productivity. When grown on soil in greenhouse longer than 5 weeks, transgenic Arabidopsis plants that over-express an ABC (ATP-binding cassette) transporter, AtABCG36/AtPDR8, produced higher shoot biomass and less chlorotic leaves than the wild type. We investigated whether the improved growth of AtABCG36-overexpressing plants was due to their improved resistance to abiotic stresses, and found that AtABCG36-over-expressing plants were more resistant to drought and salt stress and grew to higher shoot fresh weight than the wild type. In contrast, T-DNA insertional knockout lines were more sensitive to drought stress than the wild type and were reduced in shoot fresh weight. To understand the mechanism of enhanced salt and drought resistance of the AtABCG36-over-expressing plants, we measured sodium contents, and found that AtABCG36-over-expressing plants were lower in sodium content than the wild type. Our data suggest that AtABCG36 contributes to drought and salt resistance in Arabidopsis by a mechanism that includes reduction of sodium content in plants.