Although decadence is primarily the corruption of instincts in the name of moral good and the weakening of the vital forces in the individual, it has not remained limited to this scope but infected the whole culture and civilization. However, when the debates on decadence are viewed, it is seen that they are mostly focused on moral decadence. With this article, we aim to reach a full portrait of Nietzsche's critique of decadence as far as possible by shedding light on the various manifestations of decadence in culture and civilization as well as decadence in the field of morality. This can also be called making a kind of genealogy of decadence. According to the philosopher, decadence is not only represented by idealist understandings that divide life into good and evil, tending to destroy "evil," which is the necessary leaven of life. But it is also represented by moralities and cultures and civilizations that emerged based on opposition to idealism. All of these contrasting thoughts form different symptoms of decadence. In this context, the article will try to reveal that the target of the philosopher's destructive critique does not solely consist of the morality produced by the idealist interpretation and the reflections of this morality, but his critique also targets modernism rising over the destruction of idealist morality and values as well as positivist and progressive understandings that are its derivatives, such as Socialism claiming that history progresses to an ideal future, Darwinism asserting that species are constantly evolving, Kantian moralism, democracy, romanticism, and an even more extensible list.