This study aims to demonstrate the factors that cause five-year-old children to derive joy from that of other children. Examples were collected over a year with regard to a class of five-year-old children for whom the principal author was responsible, and these examples were analyzed and discussed. As a result, as potential factors prompting children to derive joy from others, analysis was carried out on behavior toward other children, the behavior’s intention, identical experience, shared aims and behavior, sustained interest in other children, and chance. It was shown that the involvement of a mix of factors caused children to derive joy from that of other children, and it was suggested that such occurrences are related to a child’s sense of being useful, and his or her empathy and sympathy toward positive emotions.