The investigation of students' conceptions of knowledge of mathematics and the process of knowing mathematics is important to provide an understanding of the phenomena behind students' performance. However, there is a scarcity of empirical investigation of students' beliefs about mathematics knowledge in the Indonesian context. This study aims to assess students' beliefs about mathematics education. The relation of these beliefs with gender, grade, and culture was also examined. Fifteen classes were selected by stratified random sampling methods. 536 students (boys = 217, girls = 319) from 8-9 grades participated in the present study. The result of this study revealed students viewed that their mathematics teachers have tried to make mathematics lessons interesting and perceived that mathematics knowledge continues to expand. Boys' students hold stronger beliefs that they can understand the most difficult tasks in mathematics than girls' students. Grade eight students have higher beliefs than ninth-grade students. Javanese students hold stronger beliefs in mathematics performance than Madurese students. The finding of this study provided information on how to design teaching and learning mathematics in the Indonesian context.