To develop and evaluate the accuracy of augmented reality (AR)-based patient positioning systems in radiotherapy. AR head-mounted displays (AR-HMDs), which virtually superimpose a three-dimensional (3D) image generated by the digital imaging and communications in medicine (DICOM) data, have been developed. The AR-based positioning feasibility was evaluated. Then, the setup errors of three translational axes directions and rotation angles between the AR and the conventional laser-based positioning were compared. The AR-based pelvic phantom positioning was feasible. The setup errors of AR-based positioning were comparable to laser-based positioning in all translational axis directions and rotation angles. The time necessary for AR-based positioning was significantly longer than that for laser-based positioning (171.0 s vs. 47.5 s, p<0.001). AR-based positioning for radiotherapy was feasible, and showed comparable positioning errors to those of conventional line-based positioning; however, a markedly longer setup time was necessary.