The aim of this study is to examine the effect of activity-based mathematics teaching on the attitudes of elementary school 4th graders towards mathematics activities and their beliefs about mathematics. The research is designed according to the quasi-experimental pretest-posttest control group design. The study group consisted of a total of 50 fourth graders, of which 25 were experimental groups, and 25 control groups. The Attitude Scale for Mathematics Activities and the Belief Scale for mathematics were used as pre-test and post-test tools for data collection. Additionally, the students' views on this application were taken at the end of the application. In the analysis of the obtained data the Mann-Whitney U test and the Wilcoxon Signed Ranks test were used. Content analysis has been used to evaluate student opinions of the application, and comments of the students were quoted directly. As a result of the analysis, it was concluded that students' attitudes towards mathematics activities and their beliefs about mathematics had a significant variation in favor of the experimental group while there was a significant difference between the pre-test and post-test average scores in favor of the final test while the experimental group's attitudes towards mathematics activities and their beliefs about mathematics. At the end of the study, it is found that the students of the experimental group have a positive opinion on these activities and also that the activities that the students intend to develop on the subject are similar to the studies activities. It is suggested that teaching with activities in which students are active is used more often in classrooms because of the positive impact on students' attitudes to mathematics activities and their beliefs about mathematics.