Existentialism is philosophy idea that places human existence as the main point, with this philosophy allowing humans to live their life as they wish because only based on what they have done during life will be the essence of humanity itself in the end. This study aims to find existentialism ideas are contained in the main character named Linda in the novel entitles Adultery by Paulo Coelho. This study applies existentialism philosophy as the main theory and also applies character and characterization theory to find out more about what existentialism ideas are from Linda through her characters and characterizations in this novel. This study also uses a qualitative descriptive method, where a novel entitled Adultery is a data source, and the data used are sourced from narrations, dialogues, words, sentences, and actions contained in the novel. This study finds several existentialism ideas are contained in Linda's character.
Keywords: essence, existence, existentialism, freedom , responsibility.