Background The relationship between patients and physicians in medical decision-making has changed in recent times. Although patients understand essential medical information, the estimation of risk/benefit of planned treatments is a difficult decision-making process for them. The research of decisional conflict targeted decision at surgery has been rarely performed. We prospectively researched decisional conflict using a questionnaire survey for patients with elective thoracic surgery and retrospectively reviewed the quantified and subcategorized data to examine clinical factors related with the decisional conflict scale (DCS) and the quality of life (QOL).Methods For patients with thoracic surgery, self-administered questionnaire surveys regarding decisional conflict and QOL were conducted at three time points: the day before surgery, at discharge, and at 3 months after surgery. The questionnaire survey of DCS is composed of five categories (uncertainty, informed, values clarity, support, and effective decision making) that use a five-point Likert-type response. QOL was measured in the Japanese version of the M.D. Anderson Symptom Inventory.Results The questionnaire surveys were performed from April 2017 to March 2019. Eighty six patients were analyzed in this study. The total DCS scores did not differ among pre-surgery, post-surgery, and 3 months after surgery (21.8, 20.3, 19.2, respectively; P = 0.48). The effective decision subscores significantly decreased after surgery (19.2, 13.4, 13.7, p = 0.041). The pain scores at discharge were significantly higher in patients who underwent thoracotomy surgeries than VATS (6.5 vs. 4.0, p = 0.013). However, the DCS scores did not show any significant difference between the surgical approaches at discharge (thoracotomy: 12.5, VATS: 13.5, p = 0.86) and at 3 months after surgery (thoracotomy: 22.5, VATS: 12.5, p = 0.11). The effective decision subscores did not show significance to post-operative complications at post-surgery before discharge and at 3 months after surgery (p = 0.94 and p = 0.40). At 3 months after surgery, the most QOL scores were significantly related to the total scores of DCS.Conclusions Patient’s own experience of thoracic surgery and post-operative management may decrease patient dissatisfaction. The findings suggest that decisional support for patients to organize their concrete perioperative management would ameliorate their satisfaction.