The purpose of this study is to clarify environmental components and assistance in order to develop four-year-old children's "germs of morality" through their interaction with others in the same or different ages. As research methods, the researcher recorded episodes of situations where four-year-old children interact with children in the same or different ages from two aspects: 1. "to see differences between right and wrong", 2. "to have feelings to consider others". In addition, the researcher examined better environment and assistance by doing childcare conferences. The result revealed, as environment and assistance for developing four-year-old children's "germs of morality", these four assistance: 1. to accept children's feelings behind their movements, 2. to help children build circumstances where they can fully tell their feelings each other and notice how others feel, 3. to recognize values each other, 4. to relate interaction with environmental components where interactions with others in different ages naturally occur. The further research clarifies how systematic "germs of morality" is developed and investigates how environment and assistance should be in order to develop them.