This paper attempts to explore paranoia and trauma as the causes of psychological monomania in Edgar Allan Poe’s “The Tell-Tale Heart.” The study focuses on the gradual development of the narrator’s paranoia stimulated by his aversive feelings toward the old man’s eagle eye. The discussion sheds light on Poe’s meticulous narrative descriptions of the narrator’s severe acute senses that make him undergo a horrible experience. The study looks into this experience as stimulation of his paranoia, which becomes the nexus of his hesitant decision to kill the old man. In this sense, paranoia and neurotic trauma will be explored as the impetus for the narrator’s monomania stirred by a re-traumatization experience. The study applies Sigmund Freud’s concepts of paranoia and neurotic trauma, as well as Shoshana Felman’s concept of re-traumatization, as a conceptual framework. Thus, these concepts will be utilized to analyze the psychic synthesis of monomania in relation to the protagonist’s gradual development of paranoia, neurotic trauma, and re-traumatization, respectively.