Tumor necrosis factor-α inhibitors are now considered as standard therapy for patients with severe inflammatory bowel disease who do not respond to corticosteroids, but they carry a definite risk of reactivation of tuberculosis. We present a case in which a patient with inflammatory bowel disease developed a de novo tuberculosis infection after the start of anti-tumor necrosis factor-α treatment despite showing negative results in tuberculosis screening. Although there are many case reports of pleural, lymph nodal and disseminated tuberculosis following infliximab therapy, we present the first case report of rectal tuberculosis following infliximab therapy.