The development of the computer technology brought reform in the field of medical equipment. Originally the mechanical ventilator was an instrument only as for running by pressure and the tool that let you breathe. However, it has a function to assist a measurement (tidal volume, peek pressure, etc.) and to wean from a ventilator. There is a case to use a mechanical ventilator for after a chest surgical operation. After the operation without the complication, it seems that there is not the special administration. However, special respiratory management is necessary in case of chronic respiratory failure and acute lung injury, acute respiratory distress syndrome. Therefore I introduce a method to use a respirator after an operation in our institution.