We investigated a influences of volcanic emissions on fogwater at the top of Mt. Akagi located in Gunma Prefecture. After September 2000 when volcanic emissions from Miyake-jima increased rapidly, SO₄^2- concentration in the fogwater became higher, and pH and the value of NO₃^-/non-sea-salt SO₄^2- (N/S) became lower than those before. Very low NO₃^-/non-sea-salt Cl-ratio (<1) was observed seven times. These cases have not occurred since 1993 when fogwater monitoring was started. It was considered that the fogwater was greatly affected by sulfur dioxide and hydrogen chloride discharged from Miyake-jima volcano. Especially on September 14, 2000, specific fogwater (pH 2.99) mostly consisting of sulfuric acid and hydrochloric acid was observed, and the N/S was extremely low (0.07). When the specific fogwater mentioned was observed at the mountain, it was considered that a large amount of sulfur dioxide was transported to Gunma Prefecture. This transportation was recognized by other research such as sulfur dioxide monitoring at the earth's surface and real-time simulation on long-range atomospheric dispersions of volcanic gases. These results suggest that such fogwater with high SO₄^2- concentration and low pH and N/S was caused by the volcanic gas from Miyake-jima.