Objective: Snack food selection is still a problem for school-aged children. The cause of problems in child snack food selection will affect the health of school-aged children. Method: The research design used is cross sectional with the Chi Square test applied to analyse the knowledge level relationship of food safety in families with the selection of school-aged children's snacks food of 110 students in grade 4 to grade 6 and the students’ mothers, selected by means of proportionate stratified random sampling at Islamic Primary School Al-Inayah of East Jakarta. The questionnaire is in the form of Food Frequency Questionnaire to measure the selection of school-aged children's snacks and Food Safety Questionnaire for family knowledge level, especially students’ mothers. Results: The results showed that 55.4% of children selected unhealthy food and their mothers’ knowledge level of food safety was 94.1%, a sufficient knowledge level. In addition, it was proved that there was no significant relationship between mother’s knowledge level with the selection of school-aged children (P = 0.690). Furthermore, it indicated that mother with sufficient knowledge has a chance of 0.605 times to have children with unhealthy food selection compared to a well-knowledgeable mother. School-aged children have been able to make their own decisions including food selection. Conclusion: The results of this study recommend to school-aged children and families, especially students’ mother about the importance of knowledge on food safety as well as safe and healthy food selection for school-aged children to consume.