This study compared the total phenolic contents and antioxidant activities of two seaweed cultivars, Undaria pinnatifida (UP) and Capsosiphon fulvescens (CF), subjected to different drying methods. UP and CF were dried under two different conditions: vacuum drying (VD) at $20^{circ}C$ and hot-air drying (HD) at $60^{circ}C$. After drying, the total phenolic content, DPPH, and nitrite scavenging activities of the water extracts were determined. Total phenolic contents were 101.94 mg/100 g for UP and 171.35 mg/100 g for CF upon VD-20, and these values were significantly decreased to 67.59 mg/100 g for UP and 141.48 mg/100 g for CF upon HD-60. UP upon VD-20 and HD-60 had 46.17% and 35.20% DPPH radical scavenging activity, whereas CF upon VD-20 and HD-60 scavenged 57.73% and 35.22%, respectively. UP upon VD-20 and HD-60 had 40.36% and 40.01% nitrite scavenging activity at pH 1.2, whereas CF upon VD-20 and HD-60 scavenged 72.35% and 55.24%, respectively. Nitrite scavenging activities of UP and CF were reduced at pH 3.0.