This study was performed to investigate the change of biologically functional compounds and antioxidant activities in Ecklonia cava with blanching times. As biologically functional compounds, the contents of minerals(K, Ca, Na, Mg, Fe, Cu, Mn and Zn), vitamins(vitamin C, β-carotene and α-tocopherol) and total polyphenol were analyzed. And antioxidant activity was determined through free radicals(DPPH radical, superoxide anion radical, hydroxyl radical and hydrogen peroxide) scavenging activity and linoleic acid peroxidation inhibitory activity. As the blanching time increased, the contents of minerals, vitamin C, β-carotene and total polyphenol were decreased however α-tocopherol was not affected by blanching time, and antioxidant activities were decreased with blanching time.