The purpose of this study is to investigate the effect of manipulatives (tangible learning materials) both on the mathematics achievement of 9th grade students. Pretest-posttest control group experimental model, which is one of the quasi-experimental research designs, was used in the study. The study group consisted of 86 ninth grade students (42 in experiment group and 44 in control group) studying in Camanlangan National High School in school year 2022-2023. As a result of the research, posttest mathematics academic achievement scores of experimental and control groups were found to differ significantly in favor of posttests in both groups. Hence, the use of manipulatives in teaching students helped improved their performance in mathematics.