This book examines the widespread protests which took place in Japan in 1960 against the renewal of the US-Japan Security Treaty and assesses their far-reaching impact. It emphasizes the scale of the protests, at the climax of which hundreds of thousands of protestors surrounded Japan's National Diet building on nearly a daily basis, and large protests took place in other cities and towns all across Japan. It considers the results of the protests, which included the cancellation of President Eisenhower's state visit and Prime Minister Kishi's removal from office, and argues that although the protests apparently failed in that the Security Treaty was renewed and the Liberal Democratic Party remained in power, nevertheless the protests brought about subtle lasting changes in Japan: they revealed many latent societal and political tensions, and they compelled the ruling establishment to reshape itself, having to take seriously non-militarization and the need to listen to the people. The events are analysed in terms of social movement dynamics, with comparative references to the Western European protests of 1968.