This study determines the body size of preteen children and conducts questionnaire investigations into the awareness of real purchasers or parents of and satisfaction with children`s clothes and fit, in order to provide the basic data for planning and setting up the size range for the preteens market in which the sales of children clothes are gradually increasing. The findings of this study are as follow: Analyzing the obesity of the children against the Rohrer index showed that almost 30% of the subjects were obese children and that it is necessary to research the sizes of the clothes for obese children. It was also found that older children selected a more appropriate clothe size. Investigations into the awareness of children on their body image found that there was a significant difference in the perception of body shape, body weight, shoulder breath, arm thickness, chest girt, waist girth, hip girth, and thigh thickness. Slim or standard type children had the greatest consideration for the length of clothes to purchase while obese children had the greatest consideration for bosom size and waist girth. However, in terms of the association between fitness and size selection, obese children did not select a bigger size but an appropriate one for their body. The findings show that it is imperative to develop appropriate size clothes for obese children.