Background: Chronic pain is a major health problem, and cognitive behavioral therapy (CBT) is its recommended treatment; however, efforts to develop CBT programs for chronic pain and assess their feasibility are remarkably delayed in Asia. Therefore, we conducted this pilot study to develop a basic individualized CBT for chronic pain (CBT-CP) and assessed its feasibility for use in Japan. Methods: Our study was an open-labeled before-after trial without a control group conducted cooperatively in five Japanese tertiary care hospitals. Of 24 outpatients, 15, age 20-80, who experienced chronic pain for at least three months were eligible. They underwent an eight-session CBT-CP consisting of relaxation via a breathing method and progressive muscle relaxation, behavioral modification via activity pacing, and cognitive modification via cognitive reconstruction. The EuroQol five-dimensional questionnaire five level (EQ5D-5 L) assessment as the primary outcome and quality of life (QOL), pain severity, disability, catastrophizing, self-efficacy, and depressive symptoms as secondary outcomes were measured using self-administered questionnaires at baseline, post-treatment, and 3-month follow-up. Intention-to-treat analyses were conducted. Results: Effect size for EQ5D-5 L score was medium from baseline to post-treatment (Hedge's g = - 0.72, 90% confidence interval = - 1.38 to - 0.05) and up to the 3-month follow-up (g = - 0.60, CI = - 1.22 to 0.02). Effect sizes for mental and role/social QOL, disability, catastrophizing, self-efficacy, and depressive symptoms were medium to large, although those for pain severity and physical QOL were small. The dropout rate was acceptably low at 14%. No severe adverse events occurred. Conclusion: The findings suggest that CBT-CP warrants a randomized controlled trial in Japan. Trial registration: University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR), UMIN000020880. Registered on 04 February 2016.