The purpose of this study was to examine the developmental process of passion. Using case study methods, the target was a physical teacher who won the award of teaching. Data collection included participant observation, in-depth interview, documented collection and so on. Phenomenological qualitative analysis was used to analyze data. The findings revealed that the development of passion toward physical activity was influenced by the role model of father and peers, interpretation of activity values by significant others, teacher's support, and autonomous personality. Furthermore, autonomy support facilitated the autonomous internalization of the interesting activity in one’s identity, thereby leading to harmonious passion. This study support the concept of passion by Vallerand et al. (2003) that autonomous internalization was found to predict the development of harmonious passion.