This study was conducted to compare the antioxidative effects of Dendranthema zawadskii var. latilobum (Maxim.) Kitam and D. zawadskii var. yezoense (Maek.) Y.M. Lee & H.J. Choi due to the harvest date. Harvested samples at May 9th (early), July 17th (middle) and September 3rd (late stage) were extracted with 80% ethanol, and biological activities and antioxidant substance contents were detected. The earlier harvested samples showed the higher moisture contents and extraction yields. DPPH radical scavenging effect of early harvested D. zawadskii var. latilobum (Maxim.) Kitam ($RC_{50}$ = $0.128;mg;{cdot};mL^{-1}$) was similar to BHT ($0.121;mg;{cdot};mL^{-1}$). ABTS radical scavenging effects of both species harvested at early stage were higher than that of ascorbic acid which was well-known natural antioxidant. However, both species harvested at late stage showed the highest $Fe^{2+}$ chelating effect, but it was lower than that of EDTA. Total polyphenol and flavonoid contents of both species were higher when samples were harvested earlier stage. However, both species harvested at early stage contained more total polyphenols (79.93 and $75.10;mg;{cdot};g^{-1}$) than flavonoids (57.84 and $54.91;mg;{cdot};g^{-1}$).