The purpose of this study was to analyze body mass index of women in their twenties and investigate the relationships of body attitude and clothing attitude. To achieve the purposes of this study, a questionnaire was conducted with 398 people from May 2 to May 30, 2013. The final data was analyzed with spss 18.0 program. The results were as follows: First, I found that body attitude had this order: Feeling fat, Lower body fatness, Salience of weight and shape, Attractiveness, Strength and fitness, and Body disparagement Secondly, there were significant differences of body attitude based on demographic characteristics and body mass index. Thirdly, I found that clothing attitude was classified into four factors of Personality pursuit, Body complement, Appearance ostentation, and Social approval. Fourthly, there were significant differences of clothing attitude based on demographic characteristics and body mass index. Fifthly, there were significant relations of body mass index, body attitude, and clothing attitude of women in their twenties. Thus, I found that body mass index and body attitude were related to clothing attitude.