Pneumatosis cystoides intestinalis (PCI) is associated with various diseases, but rarely with inflammatory bowel disease. We describe a rare case of PCI associated with ulcerative colitis. The patient was a 30-year-old man with ulcerative colitis (UC), which was in remission under immunomodulator therapy. Colonoscopic examination around 2 years after a diagnosis of UC revealed multiple hemispherical submucosal tumors (SMT) in the ascending colon and hepatic flexure, with erosion and disappearance of vascular network patterns in the rectum. PCI was diagnosed from the result of colonoscopic examination and computed tomography, and had not changed on colonoscopic examination 2 months later, without any treatment.