Ulcerative colitis (UC) is an incurable, chronic inflammatory disease of the large bowel whose etiology and pathogenesis have not yet been comprehensively explained. Tofacitinib is a small molecule Janus kinase inhibitor that was introduced for treating refractory UC. We aimed to examine the efficacy and safety of tofacitinib for the treatment of 18 patients with UC. Continuous treatment rates were 50, 38, and 33% at 8, 24, and 52 weeks, respectively. Overall, 83.3% of these patients showed tumor necrosis factor (TNF) antibody failure status. When the effective status was defined as a Lichtiger index (LI) that decreased by 3 points or more or was less than 4 points and remission status was defined as an LI less than 4 points, the effective and remission rates (%) at 2, 8, and 16 weeks were 55.5 (10/18) and 22.2 (4/18), 38.8 (7/18) and 33.3 (6/18), and 38.8 (7/18) and 38.8 (7/18), respectively. Background characteristics of 2-week responders and non-responders were compared. C-reactive protein level in responders was significantly lower than that in non-responders, and the hemoglobin level in responders was significantly higher than that in non-responders. This study provides preliminary results of the effectiveness of tofacitinib even for TNF antibody and tacrolimus failure patients.