The study is to find when and how the laughter, one of the major topic in our society, arises among young children by studying the laughter of young children in qualitative research. It gathers data through participant observation and interviewing with the teachers and 19 young children. The findings of this study are as follows. First, those young children released their laughter through imagination, boasting, making fun, playing the fool. Second, the aspects of laughter of young children are laughing in a loud voice, giggling, smiling, shrieking. The study results in that young children release their various positive and negative laughter in various ways in the classroom. Finally, the study suggests to search for proper teaching methods for negative laughter by understanding the meaning of it, and stimulate, assist the positive laughter in the classroom.