Objective: To evaluate the clinical effect of Traditional Chinese Spinal Orthopedic Manipulation (TCSOM) in treating Irritable Bowel Syndrome (IBS) in comparison with Pinaverium Bromide Dicetel (PBD), and to assess a possible cause for IBS. Methods: 60 cases of IBS patients were randomly divided into two groups: TCSOM and PBD. All patients in the TCSOM group were treated with a 5-time spinal manipulations. The symptoms of pre-treatment and post-treatment were evaluated based on bowel symptom scale (BSS) scores. A symptom improvement rating (SIR) and patient subjective assessment (PSA) were implemented in order to evaluate the effects of the treatments, and to statistically compare the two groups. Results: The symptoms of 23 patients of the TCSOM group disappeared soon after spinal manipulation and 6 cases were significantly improved. The BSS scores in the TCSOM group were significantly lower than those in the PBD group post-treatment. According to the SIR which was based on the BSS, the TCSOM research group included 14 cases with excellent results, 13 cases with good, and 3 cases with poor. Adverse side effects to the treatment were not reported. Based on the BSS, the PBD research group reported 7 cases with excellent results, 8 cases with good and 15 cases with poor. All cases were statistically analyzed, revealing a significant difference (P<0.001) between the two groups. Conclusion: The displacement of inter-vertebral disks and/or vertebra in the thoracic or lumbar region seems to be a contributing factor in the symptoms of irritable bowel syndrome. Thumb pressing manipulation on jiaji points in the thoracic and/or lumbar region can correct the displacement of inter-vertebral disks and/or vertebra, resolving the stimuli caused by pressure exerted on the nerves and vessels around the spine. So it is an effective treatment for IBS.