While difficulty with emotional regulation is well-known to be one of the mechanisms contributing to onset and maintenance of various mental disorders, difficulties in controlling both positive and negative emotions are also gaining attention. One of the self-reporting measures of difficulty in controlling positive emotions is the Responses to Positive Affect questionnaire (RPA). This study aimed to develop an extended version of the RPA by adding five questions reflecting dampening of strong positive emotion and intended to confirm its construct and incremental validity. The application of the exploratory factor analysis and exploratory structural equation model (ESEM) to 298 cyber university students resulted in a three-factor structure for the extended RPA: positive rumination, dampening, and extinguishing strong positive emotion (the 5 additional questions comprised this factor). After performing confirmatory factor analysis in the separate sample of 227 cyber university students, the suitability of the three-factor model was deemed appropriate. We also performed a hierarchical regression analysis to see if the extended RPA contributed to the explanation of the mechanism of the pathology above the previous version. As a result, the 'extinguishing strong positive emotion’ subscale made a significant additional contribution to the explanation of bipolar disorder and difficulty in controlling positive emotions beyond the existing RPA, supporting an incremental validity. Finally, this study’s clinical implications and limitations were presented, as well as suggested directions for follow-up research.