The purpose of this research is to verify the effects of forest play activity on young children's playfulness and leadership. The subjects were 40 young children from a child-care center in K city. 20 children were randomly assigned to the experimental group, and the other were assigned to the control group. The forest experience activity consisted of forest experience, forest play, nature inquiring activity, and ecosystem understanding. The activities in forest are inseparable from playing, and playing is life itself for young children. Forest experience in this activity consists of 4 steps which are first step for awaken enthusiasm: zeal in the presence of peace and tension of mind, second for concentration: can achieve dramatic enlightenment, third for direct experience: the process of deeply knowing nature and fourth for share emotion: existence of nature give impression. In results, the activity had effects on the children's playfulness and leadership. Young children explore and investigate their surrounding world in accordance with their interests and paces, and reorganize their experience to express it. Early childhood is an important time when holistic aspects such as cognition, emotion, sociality develop rapidly, and the leadership experience suggests a necessity of educating leaders who can lead changes as potent members of society and will lead the future.