From early to late childhood the brain and nervous system undergo significant development. Researchers believe that 80％ of the basic structures of the system are completely developed by the age of five and about 100％ by the age of twelve. It has also been noted that mental development happens in tandem with physical development. However, this development does not happen in isolation. Rather, it is acquired through involvement with other children, and through external information and exogenous stimuli. If children are not able to achieve sound physical growth in their childhood, they will have various physical problems in the future. More specifically, they may suffer from locomotive syndrome later in life. The significance of physical education play by pre-school children as well as physical education for school-age children lies in the children’s acquisition of physical ability commensurate with their age. If they successfully acquire this ability, this will make it more likely that the children will be physically healthy later in life. In this context, the author calls attention to the tendency among children today to get less physical exercise than in the past, discusses the need for adults to stimulate children to engage in physical education play or physical education and to watch over them. It is most important to let children’s instinctive urge for active play blossom. The author proposes that families and schools work together to improve the circumstances at schools（including nursery schools, kindergartens, and elementary schools）and to be certain children partake of daily physical education. This, the author believes, contributes to the sound development of children’s mental and physical health.