The oxygen consumption and the survival time of the blue mussel, Mytilus edulis, was determined in the sea water of low oxygen tension to study of tolerance of anoxia. Effect of low oxygen tension was observed at a value less than 0.5ml to large mussel (5.9cm shell length) and 0.1ml/l to small mussel (1.7cm shell length). After decrease of oxygen consumption, the mussel closed their shell valves and have little consumption. The survival time of the mussel in a dissolved oxygen of less than 0.07ml/l was longer in 10°C than 20°C, and the smaller mussel have the longer survival time. The longest survival time was recorded in 2.0cm shell length which survived more than 45 days at a temperature of 10°C.