In the pen shell, Atrina (Servatrina) lischkeana, oxygen uptake were examined by measuring directly the ventilation volume and the oxygen partial pressure in the respiration chamber with the closed system, and calculating the oxygen utilization and the amount of oxygen uptake at 18℃. The ventilation volume increased from 0.083l/min/kg under normoxic condition to 1.883l/min/kg (23 times that of normoxia) at 24.9mmHg. The oxygen utilization decreased from 16% under normoxic condition to 3 % at 24.9mmHg. The amount of oxygen uptake maintained almost the same level (0.53ml/min/kg ) until the oxygen partial pressure decreased to 34.8mmHg. Because the levels measured by the closed system were almost the same as those by other methods, the method by the closed system would be quite useful for the experiment on the oxygen uptake in bivalvia.