This study aims to investigate the folk beliefs in spirits of the Thai Dam people and relationships between the beliefs in spirits and the social structure of the Thai dam people. The Thai Dam have to deep-rooted belief in the spirits and it is a part of their ways of life. Although, other cultures insignificantly affect their traditional belief, the belief completely dominates the Thai Dam people’s way of life in terms of family, kinship, religion, rituals, economy, administration, education and sanitation.