The aim of this study is to examine the effect of the use of mathematics course on the prospective teachers' attitudes towards mathematics and their beliefs on the nature, teaching and learning of mathematics and also to explore their opinions about the subject course. The results of the study were also interpreted according to the academic achievement variable. The study was prepared according to the mixed embedded experimental design and the study group is formed with 40 prospective teachers who take the use of mathematics compulsory elective course in a state university in Turkey. The Mathematical Attitude Scale, the Beliefs Scale about Mathematics Teaching and Learning and Student Opinion Form were used in the study. It was found that the prospective teachers who took the subject course differed significantly and positively in their attitudes towards mathematics, enjoyed mathematics more after the course and had more confidence in themselves by defeating their fears. The use of mathematics course made prospective teachers to deviate from traditional beliefs and have more constructive beliefs about mathematics. Besides, the effect of the course on the attitudes and beliefs of the prospective teachers with different academic achievement levels did not differentiate.