The industrial oil complexes in Japan have been taking various countermeasures for prevention and reduction of disaster based on the regulations. Nevertheless, we cannot deny the possibility of breakout of severe disaster such as leakage of oil, fire, and explosion due to aging facilities, wrong operations, earthquakes and so on. Therefore, municipalities having industrial complexes are required to develop disaster prevention plans and to devise effective disaster prevention schemes. In order to effectively do that, Japan Fire and Disaster Management Agency has shown the guideline to appropriately implement risk assessment of industrial complexes for both in usual and during an earthquake based on the event tree analysis. Especially during an earthquake, the buckling of shell plate of an oil tank by strong ground motions brings the major disaster, because it is highly possible that the buckling breaks out in the vicinity of the bottom and a total quantity of oil outflows. Yamase (2006) proposed a fragility curve for the buckling of shell plate and applied it to the risk evaluation of oil tanks in Hokkaido District, northern part of Japan. However, the fragility curve was built based on only the design shell thickness data of the oil tanks in Kobe City, and the influence of aging deterioration was not considered. Then, we collected the data such as the shell plate thickness, height, diameter, and elapsed time from construction of several hundred oil tanks, and calculated the corrosion speed of the shell plates to consider the influence of aging deterioration of oil storage tanks, and newly developed a fragility curve from these data. As a result, the improved fragility curve leads to the several percent larger in the buckling outbreak probability for oil tanks built scores of years ago.Copyright © 2010 by ASME