This study aimed to clarify the relationship between serum 25-hydroxyvitamin D concentration body composition by examining male university rugby players in a cross-sectional manner. The subjects were 36 male rugby players (mean age: 20.2 years) who provided us with data regarding their body composition, blood biochemistry examination, and dietary intake frequency. Examination of their serum concentrations of 25-hydroxyvitamin D 【25 (OH) D】 showed that 58% (21/36 subjects) and 42% (15/36 subjects) had sufficient and insufficient intake of vitamin D, respectively. In comparison of serum 25 (OH) D concentrations between players in individual positions, it was suggested that the concentrations were significantly lower in the forward (FW) players compared with the backs (BK) players (p<0.01). The number of FW players with lipid abnormality was significantly higher than that of BK players (p<0.01). Serum 25 (OH) D concentrations showed negative correlations with weight, Body Mass Index (BMI), total body fat amount, and lean body weight. Multiple linear regression analysis suggested that serum 25 (OH) D concentration would be affected by BMI. The average serum 25 (OH) D concentration among obese class II – IV players was 27.8 ng/mL, which was significantly lower than that of players with a normal weight or obese class I (34.2 ng/mL, p<0.01, 33.1 ng/mL, p<0.01). These findings suggest that vitamin D intake among obese class II – IV players was not sufficient, despite the fact that their intake of vitamin D was 14.1 µg, which was much higher than the adequate intake level. In the future, further studies should clarify how increased intake of vitamin D could improve physical characteristics.