Thrombosis, especially venous thromboembolism, is a complication often associated with coronavirus disease 2019 (COVID-19). However, there have been relatively few reports of arterial thrombosis. Here, we describe a case of non-severe COVID-19 in a patient with dilated cardiomyopathy. After admission, symptoms, laboratory data, and imaging findings improved, but D-dimer levels gradually increased. Contrast computed tomography and echocardiography revealed a left ventricular thrombus. Anticoagulant treatment diminished the thrombus, and the patient recovered and was discharged. Although a left ventricular thrombus is a rare COVID-19 complication, performing appropriate diagnostic tests could improve COVID-19 mortality in patients with dilated cardiomyopathy.