Systemic erythematous lupus is a systemic inflammatory autoimmune disease that develops from drug, viral, or chemical irritants. We report a case of lupus-like syndrome after kidney transplantation with an unknown cause. A 55-year-old woman was admitted with severe myalgia, fever, and arthralgia 2 days previously. She had received a kidney transplantation 8 years ago, because an acute kidney injury had progressed to chronic kidney disease. After transplantation, she had no problems. We performed blood, urine, and sputum cultures but could found no microorganisms. We suspected a connective tissue disease, such as adult Still's disease, and performed autoantibody testing. As a result, antinuclear antibody was positive, and we diagnosed her with lupus-like syndrome due to an unknown cause. We increased the prednisolone dose and her symptoms improved.