A maxillary skeletal expander includes a pair of bodies, an extending screw adjusting a space between the pair of bodies, guide rails having both sides inserted into the pair of bodies and guiding a movement of the bodies, a key hole integrally formed with the extending screw, screw insertion portions integrally formed with the bodies and having screw insertion holes guiding mini-screws implanted to an upper jaw, arms having one end fixed to the bodies and the other end extending toward teeth, and a teeth fixing part integrally formed with the arms and fixed to teeth of a patient.
