Perceived actual body weight and perceived ideal weight were assessed in 255 Japanese children and adolescents (130 boys, 125 girls) aged 6 years through 18 years using the drawing test to clarify whether they wanted to be thinner or to gain weight. More than half (68%) of the girls attending high school and 41% of the elementary school girls perceived their ideal weight to be less than the standard. The mean difference between the perceived actual weight and the ideal weight was positive in the high school girls of normal weight as well as in the overweight girls, meaning that even the normal-weight girls wanted to lose weight. The difference was also slightly positive in the underweight girls. The difference in the high school boys was negative, demonstrating that they wished to gain weight. It is suggested that girls want to lose weight even before adolescence; this tendency becomes more prominent in the high school period and is mostly unrelated to their own weight.