Purpose: The purpose of this study is to explore psychological momentum events which influence player's performances in badminton competition and to examine in depth the player's psychological momentum experiences. Methods: A total of 83 badminton athletes over high school in Korea Badminton Association were carried out in this survey with open-ended questionnaires. And 8 adult athletes were interviewed in-depth with the guidelines based on the open-ended survey responses. The collected data was analyzed by inductive content analysis and the extracted contents from the inductive categorization were developed by deductive method. Results: The survey was conducted to analyze psychological momentum accidents which may influence on the performances of badminton players. The total of 615 raw data were collected and then categorized into 25 positive momentum accidents and 28 negative ones. The respective accidents were classified 8 general categories according to performance, opponent's performance, the flow of game, score, psychological states, physical condition, other's significant behavior and the court environment. Conclusion: Finally, this study will promote the understanding of context and environment which affect the player's performance in badminton competitions. Also, it is expected as the opportunity of increasing the interest on psychological momentum in sport psychology.