The author measured the physical status and skinfold thickness of school children who entered two primary schools in Numazu, Japan, in 1967 and 1968, during the following six years until their graduation. This study was made of the course of growth and development from the point of view of obesity which has in recent years been creating problems, with reference to the data obtained by measuring the builds of the school children by longitudinal section over the six years. The school children comprised 198 boys and 197 girls; and the boys were aged 7.02 and the girls, 7.03 on the average. The results of analysis of the data are presented below. I. General growth status of school children chosen subjects 1) The mean body heights, body weights and chest circumferences by ages and sexes which were measured by the author were mostly consistent with the means for the corresponding ages in 1968-1973 which were published by the Japanese Ministry of Education, but with a six-month lag. 2) The mean skinfold thickness of the upper arm, back and abdominal were commonly in the sequence of upper arm > the abdominal > the back and alterations with aging showed an abrupt increase at the age of 9 in both the boys and girls. II. The author classed the children by the rates of alterations in body weight by body heights into the following four groups; group A by not less than +10% ; group B by 0+9.9% ; group C by -0.1 to -9.9% ; and group D by not less than -10%. The growth statuses by these groups may be summarized as follows; 1) The mean magnitudes of body heights and body weights at the age of six tended to be in the sequence of group A >group B >group C >group D in both boys and gials, while only the body lengths of girls were in the sequence of group D > group C. The mean body heights of groups A and B were tested for singificant difference ;and it was revealed that there was a significant difference in mean body lengths at any of the ages of from six to 11 between the boys of the two groups, but a significant difference only at the age of ten between the girls of the two groups. 2) The mean skinfold thickness of each of the measured regions (upper arm, back and abdominal) of group A was far greater than that of any of the other three groups. 3) The rate of children judged as obese during the six pears was highest in group A, with 75.0% of boys and 60.0% of girls of this group judged so. This finding means the necessity of taking early measures to prevent the school children with a tendency to obesity at the age of six from getting obese. III. Twenty-five boys and 26 girls who were judged as obese during the six years were classed to the obese group, and the growth course of this group is presented below. 1) The mean body heights and body weights of this group at lower ages were smaller than the counterparts of group A by the rates of alterations in body weight by body heights, while those at higher ages tended to be greater than those of group A. 2) Alterations in the mean skinfold thickness of the upper arm, back and abdominal regions were such that the skinhold thickness increased sharply and markedly at ages of 8 to 9. 3) Alterations in annual increase in body length showed that both the boys and girls of obese group tended to be mature earlier than those of group A. 4) The incidence of obesity was high at lower ages of six to nine in both the boys and girls. Out of these children, the status of improvement of obesity at the of 11 was poor in the children judged as obese at the age of s6x. 5) The correlation coefficient between the rates of increases in body weights by body heights and the skinfold thickness (upperm arm+back) was as low as r= +0.47 in the girls at ages of 9 to 11, which appears to indicate the influence of the growth accelerating stage.