In order to produce vinegar using onions, 12 acetic acid bacteria were screened from the juice of fallen peaches, and a strain showing the highest acetic acid productivity among them was selected and identified as Acetobacter tropicalis No. 22. The culture broth containing 2.5%(w/v) of initial sugar concentration showed maximum acetic production after 10 days of cultivation, and the acetic acid was produced at the highest rate and reached the maximum acidity after 2 to 6 days of cultivation when the residual sugar and the ethanol concentration were in the range of 1.6 to 2%(w/v) and 0.6 to 1.8%(v/v), respectively. Also optimum conditions for acetic acid production by response surface method using the fractional factorial design with 3 variables and 5 levels were involved with initial ethanol content of 4.67%(v/v), initial acidity of 0.03%, and initial glucose concentration of 2.35%(w/v) and predicted level of acetic acid production at these conditions was 3.77%.