The purpose of this study was to analyze the characters of bone density according to physical grade of grade-school children. Total 10 subjects were selected from two group of gilrs in the 6th grade. Two groups consisted of 5 girls at the 1st physical grade and the 5th physical grade, who had all similar height and weight. Measurement was made for 4 regions from Lumbar Vertebra No.1 to 4 and 4 Remur regions such as neck, triangle, process and shaft of femur. And the measuring instrument was \" XR26 Bone Densitometry\" that applies Dual Energy X-ray absorptiometry. Data were statistically processed through Mann-Whitney signed rank test our of non-parametric test methods by using SPSS/PC + program. The result can be summarized as follws : 1. For LV No.1, it was found that the significant difference between two groups. the 1st group had more significant difference than the 5th group. For LV Vo.2, it was also found the difference which also means that the 1st group had more significant difference than the 5th group. For LV No.3 and 4, however, it was shown that there was not any significance between two groups, although the 1st group had a little more significant difference than the 5th group. 2. In the bone density of femur regions, it was found that the significant difference between two groups for remur neck, which means that the 1st group had more significant difference than the 5th group. Likewise, it was also found shafft repectively, which also means that the 1 st group had more significant difference than the 5th group. Thus, it can be concluded that the better the grade of physical strength grade- schoolers have the higher shows their bone density.