Emergency response to oil supply disruptions has been the core mission of the International Energy Agency (IEA) since its establishment in 1974. This brochure explains the decision-making process for collective action by the International Energy Agency (IEA). The measures that can be taken are mainly focused on the use of emergency oil reserves. Finally, the historical background of major oil supply disruptions and the measures taken by the IEA. The brochure also demonstrates the need for continued emergency preparedness, including the increasing importance of involving key economies in transition and emerging economies in dialogue on energy security. The emergency response mechanism of the International Energy Agency (IEA) was established in accordance with the 1974 International Energy Planning Agreement (I.E.P. Agreement). The International Energy Planning Agreement requires that the stockpiles held by member countries of the International Energy Agency (IEA) be equivalent to net oil imports for at least 90 days, and in the event of major oil supply disruptions, stockpiles should be released, demand restrained, alternative fuels diverted, domestic production increased or available oil shared, if necessary. To complement the mechanisms identified in the International Energy Planning Agreement, the International Energy Agency has made flexible arrangements to coordinate the use of emergency oil reserves, demand restraint measures and other measures to deal with disruptions in oil supply. The collective response of the International Energy Agency (IEA) aims to mitigate the negative impact of sudden oil supply shortages by providing additional oil to the global market through integrated use of emergency response measures, including increased supply and reduced demand. Although supply shortages may lead to price increases, prices do not trigger collective response actions, as price increases may be caused by other factors, and the objective of response actions is to compensate for actual oil shortages rather than respond to price fluctuations. We have maintained close dialogue and cooperation with non-IEA member consumer countries and coordinated collective action with major oil producers.