Soybean sprout is a traditional food and its market circulation as packed in a transparent film is increasing. To characterize the off-flavor produced from film-packed soybean sprouts, harvested soybean sprouts were stored at different temperature and oxygen conditions, and time-series changes in heads pace $O_2,;CO_2$, ethanol (EtOH) concentrations as well as sensory off-flavor levels were measured. Lower temperature resulted in lower consumption of $O_2$, lower production of EtOH and less off-flavor. No off-flavors could be detected when atmospheric $O_2$ concentration was maintained over 4%, while alcoholic-flavor and off-flavor were initiated when $O_2$ decreased down to 2% and 1%, respectively. Under low $O_2$ conditions alcoholic-flavor following EtOH production preceeded prior to sensory off-flavor detection. Various aldehydes and fatty acids such as nonylaldehyde, decylaldehyde and stearic acid were identified by GC/MS from film-packed sprouts producing off-flavors. In conclusion to suppress off-flavor, soybean sprouts should be packed in a film which can control $O_2$ concentration over 2% and stored at low temperature around $4^{circ}C$.