Background : This study analyzes changes in DPPH radical scavenging activity, total polyphenol contents, and total flavonoid contents of six different kinds of Kenaf (Hibiscus cannabinus L.) leaves which are identified as herbaceous plants, and are living in the subtropics. The data of changes in polyphenol, flavonoid contents and DPPH radical scavenging activities were analyzed, based on two different lengths of growth period.. Methods and Results : The six different kinds of cultivars ; Jangdae in Korea, and El-1, R, G-1, Ef-1, Ef-2 in the State of Israel were collected on the 43th and 62nd day from when they have planted. The collected cultivars were dried at 70℃, and 80% of methanol concentration was applied to each ground specimen. Extraction was made by immersion and filtering process at room temperature. Samples were classified into two groups, one for cultivars that were collected on the 43th day, and the other for the collection of the 62nd day. We measured the rate of DPPH radical scavenging activity, total polyphenol contents, and total flavonoid contents for every Samples. For the group of the 43th day collection, Jangdae showed the highest rate of radical scavenging activity as well as the highest polyphenol contents, and El-1had the highest flavonoid contents. For the group ofthe 62nd day collection, R demonstrated not only the highest contents of polyphenol and flavonoid, but alsothe highest rate of antioxidant activity. When we compared each cultivar from another regardless its date of collection, R resulted biggest increase in all of functional components. Conclusion : Based on the test results, useful components and antioxidant activity of kenaf leaves increase in proportion to longer growing period. Particularly, the study indicates that R can be utilized as a cosmetic ingredient crop, as the rate of increase in polyphenol and flavonoid contents were highest among the six cultivars.