[Purpose]The purpose of this study was to examine the characteristics of physical fitness, lifestyle, and appearance of unidentified complaints in young children exhibiting hyperactivity and impulsive behavior.[Method]The subjects of this study were 628 young children. We analyzed 21 items related to childrenʼs behavior, lifestyle, and unidentified complaints, and 5 physical fitness items. We used these items to compare normal young children and young children exhibiting hyperactivity and impulsive behavior.[Results and Discussion]The proportion of young children exhibiting hyperactivity and impulsive behavior was slightly larger than that in the preceding research. From the results, it seems that a considerable number of children who were not medically diagnosed exhibited hyperactivity and impulsive behavior. In addition, it was confirmed that the lifestyle of these young children was significantly unhealthier than that of normal young children. We think that young children need assistance in order to ensure both appropriate behavior and lifestyle. It is necessary to examine the influence of these behavior and lifestyle upon physical fitness in older children.