The present study was conducted to investigate the antioxidant and antimicrobial activities of green tea at different harvest time. The leaves were collected in late March(Ilro), early April(Okro and Ujeon), late April(Sejak), and early May(Eoksu and Hanra). The total polyphenol content of Sejak was highest (28.87mg TAE/g). Electron donating abilities toward $alpha$,$alpha$-diphenyl-$eta$-picyryl hydrazyl (DPPH) radical were approximately 80%. SOD-like activities were above 30%, where ujeon showed the highest activity ($38.95{pm}0.96%$). The nitrite scavenging ability was pH-dependent and shown to be highest at pH 1.2, and lowest at pH 6.0. The inhibitory effects against the angiotensin I converting enzyme were over 85%, except for Okro ($58.22{pm}4.66%$) and Hanra ($77.96{pm}3.83%$). The tyrosinase inhibition rate increased with harvest time. Okro showed the highest caffeine content ($3.86{pm}0.32%$) and had the highest antimicrobial activities against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium. The combined results of this work revealed that the antioxidant and antimicrobial activities of green tea were independent of harvest time.