This study was designed to investigate the effects of sea tangle (Laminaria japonica) extract (Dasi-Ex group: dry base 4.0%) and fucoidan-added (Fuco-I, II, III group: fucoidan of 1.0%, 2.0%, 3.0% added to Dasi-Ex) beverages on the anti-stress action. ICR male mice (20$pm$2g) were fed basic experimental diets and given free through water bottle filled with these beverages instead of water for 18 days including sociopsychological stress. Body weight gains were consistently lower in Dasi-Ex and Fuco-I,II,III groups compared with control group, expecting in a inhibitory effect of obesity. Dasi-Ex group resulted in a significant decrease of 25% in serum corticosterone (CS) secretion, while Fuco-I,IIand IIIgroups resulted in a marked decreases of 45~55% in serum CS secretion compared with control group. Noradrenaline (NA) secretions were significantly increased about 15% in Dasi-Ex group, and 20~22% in Fuco-I,II,III groups compared with control group. Significant differences in brain MHPG-SO4 levels of Dasi-Ex group could not be obtained, but Fuco-I,II,III groups resulted in a marked decreases of 20~25% in brain MHPG-SO4 ratio of brain, but Fuco-I,II and III groups resulted in a marked increases of 45~60% in NA/MHPG-SO4 ratio of brain compared with control group. These results suggest that fucoidan beverage may play a effective role in a ridding of the sociopsychological stress by pivotal anti-stress effect of fucoidan.