2016 年夏，歐盟面臨近 20 年來恐怖主義威脅的最高峰。2015 年初開始，伊斯蘭恐怖分子陸續對法、比、德等國境內大城發動恐怖攻擊，使歐洲國家陷入極度恐慌。本文從歐洲恐怖主義的歷史背景出發，討論歐洲恐怖主義意識形態基礎的轉變，並描述伊斯蘭國對歐洲的威脅。此外，歐洲外交安全政策、內部移民問題與社會問題、聖戰意識形態、網路科技等因素，皆對歐洲近期恐怖主義的發展，產生重大影響。此一波歐洲恐怖攻擊方式，主要 以孤狼式攻擊為主，而歐洲聯盟也以內部與外部行動，企圖回應此波恐怖主義威脅。未來「伊斯蘭國」可能以「理念」型式的方式發展，勢將對歐盟構成另一波更嚴峻安全挑戰。

In the summer of 2016, Europe was facing its biggest terrorist threat of the last two decades. Form the beginning of 2015, Islamic terrorists have launched a series of attacks on major cities in France, Belgium and Germany. The EU has been in a state of panic after the attacks. First, this article discusses the transformation of terrorist ideology in Europe from a historical background and describes the threat of the Islamic State. In addition, the European foreign and security policy, immigration and social problems, jihadism and internet technology all significantly contribute to the recent developments of terrorism in Europe. This wave of terrorist attacks has been dominated by so called “lone-wolf” actors. The EU has undertaken internal/external actions to respond to this wave of terrorism. Islamic State may continue to exist and develop in a form of “idea” and pose another serious security challenge to the EU.