The purpose of this study was to develop and validate a scale of teacher beliefs related to mathematics, namely, beliefs about the nature of mathematics, mathematics teaching, and assessment in mathematics learning. A scale development study was used to achieve it. The draft scale consisted of 54 items in which 16 items related to beliefs about the nature of mathematics, 23 items related to beliefs about the teaching of mathematics, and 15 items related to beliefs about assessment in mathematics learning. At the first phase, 252 primary school teachers participated and exploratory factor analysis (EFA) was performed to evaluate the structure of the scale factor. There were two factors at each scale resulted from the analysis. At the second phase, 350 primary school teachers participated and confirmatory factor analysis (CFA) was performed to confirm the factors resulted from the EFA. The result of CFA indicated that the established model had sufficient fit indices. In addition, each factor had an adequate internal consistency coefficient, which was in the range of 0.715-0.787. Thus, this scale could be a satisfactory tool to assess teachers' mathematics-related beliefs. Subsequent studies could combine these three scales into an integrated scale, to simplify statistical analysis.