“Marrowbone” the film directed by Sergio G. Sanchez, is the main source of this thesis. The story of a small family consists of four siblings, namely Jack Marrowbone as the oldest sibling, Jane Marrowbone, Billy Marrowbone, and Sam Marrowbone who have to go to their mother's childhood home because they still feel traumatized by the treatment of their biological father. That trauma made Jack depressed and made Jack's multiple personality appear. The aim of this thesis is to analyze the main causes of the multiple personality that Jack suffers from. Data was collected from scripts, dialogue and scenes from films, using qualitative methods and multiple personality theory by Deborah Bray Haddock to research this thesis. The results of the research show that Jack has three more personalities within him and these personalities are the personalities of his younger siblings who turned out to be dead. The implicationis that, bad experiences in the past can damage a person's psychology thus by examining the personality, background and past of people who experience this disorder, you can find out the causes of the appearance of this disorder.