Recently, malignant change of liver cyst has been reported. A 76-year-old female was admitted to our hospital because of ruptured solitary cyst of the liver with localized peritonitis. Nine cysts of various sizes were recognized in the right lobe and medial segment of the left lobe. Laboratory findings were almost normal. Right trisegmentectomy was performed on 10th day after onset. Histological diagnosis was solitary multilocular cyst. On 8th month after operation, left lateral segment of the liver had good regeneration and no recurrent cyst on computed tomography.