With the rapid changes that are happening in our society, there seem to be enormous changes affecting the daily lives of pre-schoolers. The disturbances in the typical life style influence the mental and physical state of these children. The necessity to increase the physical activities of pre-schoolers is strongly urged, however, previous researches focused mainly on adults and works focusing on children and the relationship of their physical activities to their life rhythm seem to be limited. Thus, this study aims to analyze the physical activities of pre-schoolers in connection with their life rhythm and to examine the special feature of this correlation. As for the results, the comparison of pre-schoolers with established life rhythm with pre-schoolers with non-established life rhythm demonstrate that the latter have more physical activities and their peak period is in the morning while the former have less physical activities and their peak period is in the afternoon. Furthermore, both of them in general have less physical activities in the morning on weekends and tend to reach their peak later than they do on weekdays. From these findings, it has been proven that physical activities of children occur in the daytime; therefore, improving their life rhythm effectively is strongly suggested.