In first and second display devices that are provided in a pair on the left and right sides, image light and external light are superimposed on each other and viewed. In this case, a parallax of an angle (the value of angle) is set by a frame unit functioning as a parallax setting unit tilting principal rays of left and right image light inwardly, and the angle of convergence of an observer is in an appropriate state in the case of viewing the image light.