-This study was designed to investigate the effect of fucoidan on the activation of macrophage and on induction of apoptosis in AGS cell. To measure the activity of macrophages, NO and TNF-α assays were performed in Raw 264.7 cell. Treatment with fucoidan significantly increased production of NO and TNF-α, indicating activation of macrophages. The result of MTT assay shows that cell viability was significantly decreased in a dose and time-dependent manner. Fucoidan increased to enhance mitochondrial membrane permeability, as well as the cytochrome c release from the mitochondria. Fucoidan decreased Bcl-2 and XIAP expression, whereas the expression of Bax was increased in a time-dependent manner compared to the control. In addition, the active forms of caspase-9 were increased, and the inactivation of Akt was decreased in a time-dependent manner. Caspase inhibitor, z-VAD-FMK, canceled the apoptosis of fucoidan, expression of Bax and caspase-9 were decrease. These results indicate that fucoidan induces activation of macrophage and apoptosis through activation of caspase on AGS cell.