Autoimmune pancreatitis (AIP) has been characterized by unique clinical imaging, immunological findings, and the effectiveness of steroid therapy. A set of clinicopathological criteria for AIP was proposed by the Japan Pancreatic Society in 2002, and AIP has come to be widely recognized among general digestive clinicians. However, the indication of steroid therapy for AIP is still not well established, and furthermore the therapeutic doses and method of administration of steroid therapy is also unclear. Recently, an epidemiological survey of all the treatments used for AIP in Japan was conducted by the Research Committee of Intractable Pancreatic Diseases, and their report “Consensus for a Treatment of Autoimmune Pancreatitis” was produced. In a comparison of the results of steroid therapy and nonsteroid therapy for AIP in relation to the rate of complete remission, the recurrence rate, and the period needed to guarantee complete remission, it was thought that the administration of a steroid should be a standard therapy for AIP. However, if the diagnosis of AIP is still uncertain, steroid therapy should be given with caution. In addition, even when AIP still appears to be possible after a course of steroid therapy, a re-evaluation should be carried out taking pancreatic carcinoma into consideration. An initial steroid dose of 30–40 mg per day is recommended. With continuous and careful observations of the clinical manifestations, laboratory data, and imaging findings after administration of the initial dose of steroid for 2–4 weeks, the quantity of steroid can be reduced gradually to a maintenance dose in 2–3 months, and then reduced to 2.5–5 mg per day after remission. The recommended period of maintenance treatment is still unclear, but the administration of the steroid could be stopped after a period of about 6–12 months of treatment, although the patient should be monitored for clinical manifestations of improvement. In addition, the patient's progress should be followed taking recurrence into consideration. In order to evaluate the effectiveness of steroid therapy, follow-up observations should include biochemical examinations of blood findings such as serum γ-globulin, IgG, and IgG 4, imaging findings, and clinical manifestations such as jaundice and abdominal discomfort.