Long coriander leaves (Eryngium foetidum L.) have become increasingly familiar as culinary herbs in Japan. To investigate the overall aroma characteristics of Japanese long coriander, the volatile composition from different extraction methods was investigated by GC, GC-MS, and GC-O. (E)-2-dodecenal with fruity, sweet and sour notes was found as the major component with the highest flavor dilution factor independent of the extraction methods, and played an important role in the aroma quality. Moreover, the existence of aliphatic aldehyde reductase and aldehyde dehydrogenase was found for the first time in the long coriander herb. The formation of alcohols and acids from their corresponding aldehydes in the volatile concentrate due to the enzymatic activities was observed and found to affect the overall odor of the herb.