Oral direct-acting antivirals (DAAs) are the main therapy for hepatitis C virus (HCV)-associated liver disease in Japan. Moreover, many DAAs include an indication for compensated liver cirrhosis. However, patients with decompensated HCV-associated cirrhosis have hitherto not been indicated for therapy with DAAs. Recently, a new DAA, sofosbuvir/velpatasvir (SOF/VEL), was indicated for decompensated HCV-associated cirrhotic patients. Actually, it has been shown to eradicate HCV in many cases. However, it is not clear whether hepatic encephalopathy, ascites, and pleural effusion in patients with decompensated HCV-associated cirrhosis disappear by SOF/VEL treatment. Recently, we encountered a decompensated HCV-associated cirrhosis patient who showed the disappearance of hepatic encephalopathy, ascites, and pleural effusion with marked improvement of serum ammonia level, albumin level, prothrombin time, and platelet count after the eradication of HCV by the administration of SOF/VEL. Her consciousness was cloudy and it took many hours for the preparation of each meal just before SOF/VEL treatment, but after the disappearance of HCV-RNA by the therapy, her consciousness became clear and she could prepare meals in a short time. This case suggests the possibility of improvement from decompensated HCV-associated liver cirrhosis to compensated liver cirrhosis with disappearance of hepatic encephalopathy, ascites, and pleural effusion by SOF/VEL therapy.