In this study, as the water temperature rises due to climate, we tried to reset the 50% lethal temperature and critical water temperatures of the ark shell, Scapharca subcrenata. Determine the effect of high water temperatures on the survival of the ark shells, they were exposed for 7 days at 26, 28, 30, 32, 34 and 36℃. As a result, the survival rate was higher than 90.0% from 26 to 32℃, and the mortality rate appeared rapidly at 36℃, and all of them died on the 5th day. Based on this, the 50% lethal temperature (7 day-LT50) was 35.7℃ and the critical water temperature was 36℃. In order to analyze the cause of death of S. subcrenata at the aquaculture, thought that long-term and combination factors should be analyzed.