Background: The current phenomenon, children of elementary school age generally has a high risk of caries, because of their habit on consuming cariogenic foods and drinks (such as candy, chocolate, biscuits, etc.). Dental caries can be prevented early by maintaining dental and oral hygiene, as well as avoiding foods and beverages that contain cariogenic ingredients. The purpose of this study was to find out whether there was an impact of using illustrated storybook media on caries prevention education by avoiding cariogenic foods in elementary school students. Method: The research's design was quasi-experimental with a non-equivalent control group design. The intervention and control group were elementary students in the working area of Kedungmundu Community Health Center, Semarang City. Data analysis included univariate and bivariate analysis. To find out whether there is a difference in knowledge before and after the intervention, the Wilcoxon test was applied. To find out whether there were differences in knowledge between those who received the intervention and those who did not receive the intervention, the Mann Whitney test was employed. Result: The data analysis showed that the differences in knowledge before and after getting an education about prevention of caries by avoiding cariogenic food in students in the intervention group had a p-value = 0.000. The difference in knowledge of students in the group who got and who did not get the educational intervention, the p-value = 0.000. Conclusion: There are differences in knowledge before and after getting an education about prevention of caries by avoiding cariogenic foods using illustrated storybook media. There is a difference of knowledge in students who get and who do not get an educational intervention.