It was sought to know the epistemology of the teachers on school mathematical knowledge. The study was framed in the Socioepistemological Theory, understanding mathematics as a human activity from epistemic relativism. This qualitative study used microscopic analysis to form categories and then dialectically analyzed those categories. The investigative interest arose when observing the influence of Eurocentrism, the mono epistemism of the school and the absence of some knowledge in teaching. The epistemology of the teacher influences his teaching and affects the school model as a tool for change or social continuity. The results showed that teachers mostly understand mathematics as a priori knowledge, assigning to human action the role of discovering, interpreting or formalizing it.