Purpose: Traffic accidents are the major cause of death in children. Car seat usage in children is important to reduce the risk of death or injury caused by traffic accidents. This study aims to analyze the trends of car seat use among children ages under 6. Methods: This study adopted a cross-sectional study utilizing the Korea National Health and Nutrition Examination Survey from 2015 to 2019. In total, 1,999 responses were included for the analysis. Factors associated with car seat use were age, sex, body weight, height, family type, household income, and monthly household income. Regression analysis was used to compare the car seat use before and after the revision of the Road Traffic Act (2015∼2018 vs. 2019). Results: We found that car seat use was increasing by year, age, region, and household income. Car seat use was higher after fines increased in 2019. Age and body weight had negative association with car seat use, while height and household income had positive association with car seat use. Conclusion: Car seat use increased from 2015 to 2019 and is associated with different ages among children and household income. Further education and promotion that describes the safety benefits to children from car seat use are needed.