In modern medical practice it is not uncommon for a patient to be treated independently by several physicians at various stages. A situation may arise in which the combined negligence of different physicians—who are not in partnership or otherwise vicariously liable for each other’s acts—results in one indivisible injury. These physicians, although acting independently of each other, have sometimes been sued as joint tortfeasors, each allegedly jointly and severally liable to the patient for the entire injury.There is a principle that restrict or exclude criminal negligence in corporative division of labor. It is so called as ‘Principle of Trust’. As this principle, the physician who trust the other physician acts without negligence in the other physician’s division of labor is not liable. There is some cases that considered ‘Principle of Trust’ in judging criminal negligence in Korea. We will review two remarkable cases. The first case(2009do7070) is that the physician who operated cesarean delivery and transfered the patient to the upper hospital is liable for negligence of preparing transfusion and explaining to the physician of upper hospital. The other case is 2008na46021, the fact may be summarized as follows. The patient who was presumed having breast cancer through biopsy of ‘Y hospital’, she transferred hospital and had operation to remove her breast in ‘S hospital’. After operation, it is confirmed that there is no cancer cell in her breast. In fact, the cells for biopsy was changed with another women’s at the clinical laboratory of ‘Y hospital’. This case is still remained in court.