<p>Purpose</p><p>Mental health problems such as postpartum depression have been recognized as a public health problem not only in Japan but also in other countries. Cognitive-behavioral therapy (CBT) is one of the methods to support expectant and nursing mothers with mental health problems. In this study, we conducted a web-based training course for midwives to acquire basic knowledge of CBT and aimed to clarify the changes in knowledge of CBT and confidence in CBT practice before and after the training.</p><p>Methods</p><p>We conducted a web-based survey of midwives who participated in the training before and after the training. The survey consisted of participant characteristics, a knowledge test with 13 items about basic knowledge of CBT and 18 items about knowledge of perinatal mental health, totaling 31 items, with a score range of 0 to 31 points; the confidence in CBT practice consisted of 8 items regarding CBT skills, with a 4-point Likert scale and a score range of 8 to 32 points. A correspondence t-test was used for analysis.</p><p>Results</p><p>Twenty-two midwives responded to the survey (response rate 55%), and 19 who responded before and after the training were included in the analysis (valid response rate 86.3%). The mean score of the knowledge test was 25.8 (SD=0.7) before training and 27.1 (SD=0.4) after training, with no significant difference (p=0.08). The overall percentage of correct answers was 83.4% before the training which increased to 87.4% after the training. The mean score of basic knowledge of CBT was 9.7 (SD=2.3) before the training and 12.0 (SD=0.8) after the training, with a significant difference (p=0.001). The mean scores for the 18 perinatal mental health questions were 16.1 (SD=1.4) before training and 15.1 (SD=1.7) after training, with no difference (p=0.60). The mean score for confidence in CBT practice increased from 19.3 (SD=5.2) before training to 23.8 (SD=4.0) after training, with a significant difference (p=0.001). In the item of confidence in CBT practice, the item that increased the most was the Socratic question and answer method.</p><p>Conclusion</p><p>After the training, the participants' basic knowledge of CBT and confidence in CBT practice increased. In the future, based on the knowledge acquisition status of the participants, it is necessary to re-examine the knowledge required for CBT practice and to explore the contents and methods of training, including the acquisition of CBT skills, with the aim of promoting the use of CBT in clinical practice.</p>