Indonesia has a wide range of swampy lands that need to be recovered for safe agriculture. The swampy lands and vegetation are a source of soil contamination through root exudates that need serious improvement. The plant exudates in soil could disturb seed germination. This study aimed to determine the effect of ethanol vapor treatment on the decrease in the vigor of four soybean seed cultivars. This study used a randomized block design with two treatment factors, namely ethanol-based ageing treatments as the main factor and cultivars as subfactor. The observation variables consisted of the percentage of germination, growth rate, vigor index, sprout length and sprout dry weight. The results showed that there was an interaction effect between fast ageing time and ethanol treatments and soybean cultivars which caused a decrease in the seed vigor. The soybean seeds of the cv. Gema was able to maintain more vigor compared to the cv. Grobogan which experienced more decline in germination. The 5 minutes of ageing time induced fewer damages with the highest vigor while 20 minutes of ageing the seeds induced maximum damage with the lowest seed vigor.