Footprints were obtained from 79 elementary school children aged 7 to 10 years to study about foot arch development period in children. By an analysis of plantar measurements and arch classification on the footprints, results were as follows. 1) The highest rate of foot arch was observed in 7-year-olds with 50% possessing normal- or high-arch type. Incidence of walking with all toes in contact with the ground was lowest in this age group (25%).2) Rate of foot arch was low in 8- and 9-year-olds, and flat feet were present in 25% of both boys and girls. 3) In 10-year-olds, rate of foot arch was high and high arch types were appeared. 4) In 9- and 10-year-olds, a gender difference was observed in number of toes contacting the ground and high arch incidence, with greater prevalence of high arches and floating toes among boys. These findings suggest that 8 to 9 years old is the period in which the foot arch develops and that the development is complete by about 10 years of age. It was also suggested that the foot arch development is greatly affected by active use of the feet such as by playing outdoors and that an adverse effect of floating toes occur by wearing shoes.