We reported a case of dermatomyositis (DM) with liver disturbance in a 50-year-old Japanese female. She presented with fever, muscle weakness, and typical DM rashes. On clinical and serological examinations, the liver impairment was initially diagnosed as probable autoimmune hepatitis, which was denied by a histological study despite positive anti-liver-kidney microsome-1 antibody. Finally, she was diagnosed as having DM with "liver disease associated with rheumatoid diseases", and treatment with oral prednisone (40 mg/day) achieved normalization of liver and muscle enzyme levels as well as improvement of symptoms associated with DM. Liver involvement in patients with polymyositis (PM)/DM has not been well described and is considered to be uncommon. Full clarification of the etiology of liver impairment with a histological examination in collagen diseases including PM/DM is useful to determine the proper dose of corticosteroids for the treatment of collagen diseases and their liver complications.