The goal of this research is to study the social phenomena related to the motivation of women in performing the role of mamak (uncle, mother’s brother), and the effect of this on the matrilineal system which is actualized in local Minangkabau literature. The research uses a qualitative method and a content analysis with an approach of structuralism and literary sociology. The research data source is six titles of local Minangkabau literature chosen based on purposive sampling. The data analysis uses intrinsic and extrinsic methods. The research results show seven causative factors related to the decline in the role of mamak and two causative factors related to the motivation of women in performing the role of mamak . The values contained in the motivation of women performing the role of mamak include courage to defend justice, an unyielding spirit, and responsibility to family. This influences the system of values in the matrilineal system of Minangkabau, by weakening the role of mamak , strengthening the role of the nuclear family, and causing a shift in the kinship structure within the family. Keywords: Minangkabau women, role of mamak , local literature, motivation. DOI: 10.7176/ADS/83-03 Publication date: July 31 st 2020