The etiology of Sjögren's syndrome (SS) remains unclear and is associated with many other autoimmune diseases. In particular, symptoms of SS are not apparent when steroids are already being administered for other autoimmune diseases. This report documents a case of autoimmune hepatitis with SS, which was diagnosed on the basis of the worsening of unilateral pleural effusion after the discontinuation of steroids as well as the manifestation of symptoms, such as dry mouth. Adrenal insufficiency due to the discontinuation of steroids was assumed to be the cause of the worsening, rather than infection stress, because no indicators of infectious diseases were observed. The diagnosis of SS was confirmed via lip biopsy examination and anti-SS antibody positivity. Re-administration of steroids rather than antibiotics drastically reduced the pleural effusion and improved the dry mouth symptom. SS with pleural effusion in a case of autoimmune disease was reported to show both unilateral and bilateral pleural effusion predominantly containing lymphocytes. SS with pleural effusion may be more common than expected and should be differentiated from traditional SS. Moreover, biopsy examination should be considered if necessary because the condition might remain latent when steroids are administered.