This study was conducted to investigate the effect of blanching time on changes of hazardous factors in leafy vegetables treated by systemic and non-systemic pesticides. Changes of hazardous factors in leafy vegetables treated by systemic and non-systemic pesticides showed the same trend. In changes of microbial counts in leafy vegetables according to blanching time, the total plate count was significantly decreased by blanching and total coliforms were not detected in any of the vegetables. In traceable metal contents of fresh vegetables before washing, the levels in spinach, chard and whorled mallow were 0.042, 0.040 and 0.032 ppm for Pb, 0.020, 0.023 and 0.019 ppm for Cd, and 0.029, 0.034 and 0.030 ppm for As, respectively. Therefore, the levels of Pb, Cd and As in leafy vegetables were very traceable and in terms of food safety there was no problem. On the other hand, the traceable metal contents in leafy vegetables did not show significant difference by blanching and blanching time. Nitrate contents in fresh vegetables before washing were detected at traceable levels. The nitrate contents in spinach, chard and whorled mallow were significantly decreased by $22\%,;17\%;and;14\%$ after blanching time of 5 min, 9 min and 10 min, respectively.