This studi aims of this research is to explain the social structure and function of the people's belief in the expression of prohibitions regarding pregnancy, childbirth and breastfeeding for the people of Lombok Jorong Irian Kenagarian Ujung Gading Hamlet, Lembah Melintang District, West Pasaman Regency. the type of research used is literary research with descriptive methods. The research data were obtained from interviews with several informants. Data collection was carried out through the stages of recording interviews, recording the necessary data, and transcription into written form. while data analysis was carried out with the data inventory stage, data analysis stage, discussion stage as well as conclusions and reporting. The findings of this study are: (1) the structure of the people's belief in the expression of prohibitions regarding pregnancy, childbirth and breastfeeding The people of Lombok Jorong Irian Kenagarian Ujung Gading Hamlet, Lembah Melintang District, West Pasaman Regency are divided into two parts, namely the structure of two parts and thethree-part structure.(2) The social function of the people's belief in expressing prohibitions regarding pregnancy, childbirth and breastfeeding of the Dusun Lombok Jorong Irian Kenagarian Ujung Gading District, Lembah Melintang District, West Pasaman Regency, is divided into four, namely strengthening beliefs, imaginary projection systems, educating,and forbid.