Modern orthognathic surgery is said to be clean contaminated due to the intraoral means of access. Complications after orthognathic surgery, a common operation, occur about 10% of the time. Actinomycosis, a rare specific infection, plays a negligible role. Diagnostically, it should be differentiated from other infections that occur a long time after the operation. Three cases of actinomycosis that occurred after orthognathic surgery were observed, and therapeutic measurements are described case by case.