Hannah Arendt is an intellectual who has faced the problem of evil more than anyone else, and if we take Arendt’s reflection seriously, the reflection of the evil she worked on must convey some significance to us as we attempt to understand the world. This research argues that Arendt’s reflection on evil is still relevant today, and in particular can provide critical advice on the ills of evil in the Sewol ferry disaster has not ended. Uniquely, Arendt saw the intention of realizing the concept of absolute good and evil, such as religion or ethics, in the political realm, resulting in the destruction of the public realm, which can be said that the reflection on evil, along with the theory of behavior and public sphere, forms an important axis in the Arendt’s political philosophy. It is no exaggeration to say that it is unreasonable to understand her political philosophy without understanding her theory of evil, since Arendt thought politics was the best way to avoid evil. This study focuses on three issues. First, what Arendt’s warning about the uncritical involvement of good and evil in politics in the traditional way is discussed. Second, we will examine the radical and absolute evil that Arendt became interested in after actually experiencing totalitarianism. Finally, as Arendt observes the Eichmann trial, a remnant of totalitarianism, she further refines his position on evil, which is the concept of the banality of evil. This paper reflects on the problem of evil of the Sewol ferry tragedy, the biggest trauma of our society, through Arendt’s discussions of evil.