The study aims to investigate the mathematics anxiety-apprehension of prospective primary school teachers and its causes. The mathematics anxiety-apprehension of the prospective primary school teachers was analyzed using a number of variables. The prospective teachers were asked to provide written answers to open-ended questions about the causes of their mathematics anxiety. The study used mixed method research design. The quantitative data for the prospective teachers' mathematics anxiety-apprehension were collected using the Mathematics Anxiety-Apprehension Scale developed by Ikegulu (1998) and translated into Turkish with validity-reliability analyses by Özdemir and Gür (2011). The qualitative part of the study used the phenomenological method, and the prospective teachers' metaphors for aspects of mathematics were collected as data. The participants in the study were third-and fourth-grade prospective teachers studying in the Primary Education Department of the Necatibey Faculty of Education at Balıkesir University. They were chosen by simple random sampling. The independent samples t-test was computed to analyze the quantitative data, and descriptive statistics were used for the qualitative data. The study found that the mathematics anxiety-apprehension of prospective primary school teachers who were Anatolian high school graduates was significantly lower. Mathematics anxiety-apprehension did not vary by gender, and the third-grade prospective teachers had significantly higher mathematics anxiety-apprehension. The causes of the prospective primary school teachers' mathematics anxiety-apprehension were found to be related to teachers, prospective teachers, the examination system, mathematics program-related and school facilities-related causes. The prospective primary school teachers often used metaphors such as life, crossword puzzle, game and human for each sub-theme, and 166 metaphors for mathematics were identified. The themes with the highest number of metaphors were basic principles of mathematics teaching, basic mathematical skills and mathematical knowledge, respectively.