Ulcerative colitis (UC) and Crohn's disease (CD) is an inflammatory bowel disease of unknown aetiology characterized by periods of remission and acute episodes of relapse with severe inflammation in the colonic mucosa. Conventional treatments for UC and CD include 5-aminosalicylate, corticosteroid, elemental dietary treatment, corticosteroid, and thiopurine (azathioprine). Recently, new immunomodulators and anti-TNFa agents, such as tacrolimus, infliximab, and adalimumab have been developed and these treatments are available to be treated for patients with refractory UC and CD. Conventional step-up treatment has been replaced by top-down treatment using biologics. Infliximab and adalimumab induce not only clinical remission but also improve relapse rates and surgical rates. Endoscopic mucosal healing predicts short- and long-prognosis for both of these diseases, thus recent treatment strategy should be aimed for endoscopic remission. Although biologics is useful for patients with UC/CD, secondary loss of responses (LOR) for biologics has been partly observed in CD patients. Measuring anti-infliximab antibodies and concentration of infliximab trough level may help considering treatment strategy for patients with LOR.