This study was intended to improve the ability in understanding mathematical concepts through digital-based comics. The population in this study were the fifth grade elementary school students in the Genuksari area, Semarang, Indonesia, totaling 120 students, with sample of 58 students. The instrument used in this study was a test of the ability to understand mathematical concepts. Meanwhile, the research data were analyzed using different test (t-test) and normalized gain test. The results showed that the t test results showed t-count = 39.74 > t-table = 1.98 at the significance level α = 0.05. This means that the use of digital-based comic teaching materials is better than conventional books. Meanwhile, the results of the n-gain test showed that the pretest value was 61.17 and the posttest value was 90.96 with an average value of 0.73 increase in the high category. So, it can be concluded that the teaching materials developed could increase students' ability to understand mathematical concepts. Therefore, the use of teaching materials digital-based comics is very effective and becomes an alternative in increasing the ability to understand mathematical concepts in elementary school students.