The purpose of this study was to explore on how children in group theraplayⓇ could reveal phenomenologically their own emotion, behavior as well as social interaction, to interpret it from the perspective of neuroscience. When it comes to social interaction, the way of approaching this research might be one of the free variation. Conducting group theraplayⓇwith 4 year-old 8 children, emotions and behaviors in the process have been described as a phenomenological perspective, analyzing those and interpreting those neuroscientifically. Results were as below. There were changes of expression and behavior as well as pleasure, accompanying with increasing of eye contact and laughing. It was based on inter-subjectivity, inter-regulation, inter-attunement as well as imitation. On the other hand, Competitive or negative emotions and behaviors were reduced. This is due to the fact that Group TheraplayⓇ was “involved in the expansion of children s tolerance.” Also it was because of the pursuit of resonance between the right and right brains as well as the enjoyable play experience involved in bottom-up brain development. This study was meaningful in that it attempted a method of free variation of social interaction, and made possible the encounter between theory and practice through multidisciplinary connections.