The purpose of this study is to develop a science e-module based on scientific approach on the topic of the cahaya dan alat optik in a fourth grade of elementary school which is valid, practical, and effective. This development study used the ADDIE with several steps; analyze, design, development, implementation, and evaluation. This study was conducted on 4th grade students in SD Dwijendra Denpasar. The data collection used rating scale, questionnaire, and essay test methods. The results of the validity test of two material expert lecturers got an average percentage of 92% with very good qualifications. The results of the validity test of two media expert lecturers got an average percentage of 90% with very good qualifications. The practicality response of the product from four homeroom teachers for grade IV SD Dwijendra Denpasar, got an average percentage of 90% with very practical qualifications. The results of the product effectiveness test based on students' understanding of science concepts got a percentage of effectiveness about 86.26% with high effectiveness criteria. Based on this analysis, it can be concluded that the development of a science e-module based on scientific approach on the topic of cahaya dan alat optik conforms to be valid, practical, and effective. Thus, the scientific approach on science e-module on the topic of the cahaya dan alat optik is appropriate to be applied in fourth grade elementary school learning.