Cytomegalovirus (CMV) retinitis rarely occurs in patients with connective tissue disease. We present a rare case of CMV retinitis in a patient with dermatomyositis. A 38-year-old man was admitted due to blurred vision and floaters of right eye. He had been diagnosed with dermatomyositis and taken prednisolone and immunosuppressive agents for 10 months. He was diagnosed as having CMV retinitis based upon ophthalmologic examination, decreased CD4+T cell count, and positive IgM anti-CMV antibody. Intravenous ganciclovir was administrated with cessation of immunosuppressive agents for 40 days and the lesion did not progress. This is the first report of a CMV retinitis that developed in a patient with dermatomyositis.