Good snack consumption behaviors are important among elementary students because snack provides additional energy and nutrients and because good dietary behaviors should be formed during early stages of life. This study investigated, among elementary school students, 1) snack consumption behaviors, 2) snack-related nutrition knowledge level, and 3) relationships between snack behaviors and snack-related nutrition knowledge. A convenience sample (N = 372), drawn from 5th and 6th graders of an elementary schools in Siheung-si, Gyeonggi-do, completed a pre-tested questionnaire. More than 85% of the participants snacked more than once per week. Most (77%) had their snacks at home. Fruit and fruit juice were the most frequently consumed and the most liked snack items. Taste was the most important in choosing a snack item closely followed by health/nutrition. Snack-related knowledge level was relatively high and the participants obtained their nutrition knowledge through mass media (30.4%) and family/friends (29.0%). Snack-related nutrition knowledge level and snack consumption behaviors showed positive relationships in various areas such as choosing more nutritious snack items and checking nutrition labels. Although this study was limited by its cross-sectional study design, these positive relationships suggest that better nutrition knowledge could result in better behaviors. Results of this study indicated that factual nutritional knowledge has been well transmitted to students. Therefore, future nutrition education on snacking could focus more on providing problem-solving and operational knowledge.