Objective The purpose of this study was to develop a Brooding Scale (BS) and to confirm its psychometric properties. Methods A preliminary questionnaire was developed based on a literature review and face-to-face interviews with healthy subjects. To evaluate reliability and construct validity, a 15-item BS was administered to 124 healthy subjects. Convergent validity was tested by assessing the relationship between the BS and the Ruminative Response Scale (RRS). Discriminant validity was confirmed in 58 patients with schizophrenia. Results The internal consistency for the BS was excellent. An exploratory factor analysis yielded two factors: the emotional (six items) and cognitive (five items) domains, which explained 33.83% and 23.69% of the variance, respectively. The BS total score and scores for factors 1 and 2 showed significant positive correlations with the RRS. The total score and sub-factor scores of the BS were significantly higher in patients with schizophrenia than in healthy subjects. Conclusion The BS can be used as a reliable and valid tool to assess brooding in healthy adults. In addition, it had good discriminant validity for patients with schizophrenia.