In the interaction between characters in the novel, narratives and utterances that express emotional reactions are unavoidable, so affect that reflects the evaluation of the main character in dealing with every conflict in the story becomes interesting to study. The objectives of this research are: (i) to identify the types of affects used to portray the devotion of the main character, (ii) to know the role of affect in constructing the main character's devotion, (iii) to analyze the use of affect in constructing the main character's devotion through each stage of the novel The Devotion of Suspect X. This study uses a descriptive qualitative method by applying a Systemic Functional Linguistics approach. The location of the study is in the form of a novel entitled The Devotion of Suspect X. The data source can be the social structure in the novel. This study uses purposive sampling because it only involves one location, which is the novel, and collects data based on the research objectives. The researcher used four major stages of analysis, which consist of domain analysis, taxonomy analysis, componential analysis, and cultural theme analysis. From this study, the affect expressions used by the main characters at the orientation, complication, evaluation, and resolution stages resulted in a total of 48 affect data which plays a role in portraying devotion. So, it can be concluded that the main character’s devotion is built through the expression of affect at each stage related to the components that make up devotion.