The Japanese diagnostic guidelines for autoimmune hepatitis (AIH) were proposed in 2014. This study aimed to determine the trends and characteristics of AIH based on a Japanese nationwide survey. Data for 796 patients who were newly diagnosed with AIH from 2014 to 2017 were collected from January to March, 2019 from 54 hospitals throughout Japan. Clinical characteristics, including treatment, were compared with those reported in a prior 2015 survey. The population had a median age of 63 years at diagnosis, and the male to female ratio was 1:5.3. The numbers of women was significantly lower in this survey than in the 2015 survey. Moreover, the incidence of AIH with histological acute hepatitis increased significantly from 11.0 to 21.7%. The changes in the laboratory findings, such as in transaminase and immunoglobulin G levels and antinuclear antibody titers, as well as in prednisolone treatment, reflected an increasing incidence of acute AIH. The clinical characteristics of AIH changed rapidly, in parallel with the increasing incidence of acute AIH. The elucidation and diagnosis of AIH with acute hepatitis are important in the management of AIH.