Burning mouth syndrome (BMS) is characterized by a chronic, ongoing sensation of intraoral burning or discomfort without causative lesions. This study sought to examine the relationship between personality traits in patients with BMS using the Rosenzweig Picture Frustration (PF) study, a projective psychological test, and their progress in treatment. Data were collected from outpatients diagnosed with BMS at our clinic between April 2017 and March 2021. The data were analyzed for 28 patients with BMS, of which nine showed improvement earlier than three months (early responders; ER), and the others did not (non-early responders; NER). The mean visual analog scale (VAS scores for BMS pain at the first visit were 52.8 in the ER and 59.6 in NER (n.s.). No significant differences were detected in the type and direction of aggression between ER and NER in the PF study. In contrast, the group conformity score of the ER (63.7%) was significantly higher than that of the NER (51.4%). Personal traits reflected in the PF study may have affected the course of improvement in the BMS. To understand the characteristics of patients with BMS and achieve more favorable treatment outcomes, further study on their personality organization is necessary.