We experienced a case of cardiac rhabdomyoma,which is incidentally found at perinatally checked sonography.The cardiac rhabdomyoma is the most common cardiac tumor of infants & children, and second most common cardiac tumor of all age groups, which is usually multiple in the case of 90%, invariably involves the ventricles affecting the left & right side equally. In more than fifty percents, the size of cardiac rhabdomyoma is enough large to threatening the life of newborn within 24hrs of birth. Cardiac rabdomyoma is actually a myocardial harmatoma rather than a true neoplasm,because of the finding of complete lack of mitotic activities. Recently,more advanved instruments such as ultrasonography or echocardiography allows to us early detection & surgical intervention of this tumor. In our case, the tumor was found at both ventricles, which occupied nearly total chambers of both ventricles. The patient was operated on 3 day after birth. The operation was removal of the tumor through left ventriculotomy and right ventriculotomy respectively. He expired in the immediate postoperative period due to low cardiac output syndrome, despite of massive inotropic agents.