Cutaneous lupus erythematosus (CLE) is a rare, potentially disfiguring, chronic autoimmune disease with extremely variable skin and mucosal membrane manifestations. Hydroxychloroquine (HCQ) is an antimalarial drug that has been used in various countries to treat autoimmune diseases including CLE. HCQ was banned for a long time in Japan because of severe chloroquine retinopathy and was reapproved as a first-line treatment for CLE in 2015. There are no case reports describing the effectiveness of HCQ for CLE with oral mucosal lesions in the dental field. We present a case of CLE whose oral lesions were successfully treated with HCQ.