The purpose of this study was to examine how elementary students’ physique, physical fitness, and body composition change each stage of their physical development. For this purpose, 180 elementary school students (1­6 grades) were compared and analyzed. Using the data, mean (M), standard deviation (SD), and the F value were extractedand one-way ANOVA was implemented to examine difference between ages. In result of the one-way ANOVA, significant differences were post-examined by Scheffe. The significance level of all statistics was α<.05. The following lists the conclusion of this comparative analysis: First, in result of the comparative analysis, there was significant difference between male and female students in both weight and height (physique categories). This tells us that male students grow in height first and then in weight, whereas female students grow in both height and weight at the same time. Second, both male and female students showed significant growth in the categories of physical fitness 50m track, sit-ups, long jump, 1,000m track, and crunch-ups. However, their overall physical fitness has decreased compared to the past. Considering that students increase in body fat rather than body muscles, the reason of it would be students’ reducing hours of physical activities or improper eating habits. Third, there was a significant difference between male and female students in body composition such as moisture content in cells, moisture content outside cells, protein, minerals, and body fat. This is probably because proper development has constantly increased students’ height and weight. In case of male students, body fat generally increases as they grow, but body fat around the abdomen area stays consistent. This means that their body fat accumulates in areas other than the abdomen area. For female students, body fat decreases from 5th grade to 6th grade, probably because this is when they gain interests in appearance and body figure. Fourth, it was found that male students gain strength in arms and legs and female students gain strength in right legs. However, male students tend to lose strength in arms and legs as they grow. It is probably because lack of physical activities and excess calorie intake accumulates more body fat compared to body muscles. Female students also lost physical fitness in lower bodies, because they are not using their legs as much as male students do and are accumulating more body fat in the lower body than they are in upper body. As proven above, elementary students’ physique is becoming taller and heavier, but their physical fitness, and body composition (obesity), and balance have worsened. ※ Key Words : physique, physical fitness, body composition, elementary school students