An optical element includes a plurality of partially reflecting mirrors provided in parallel to each other with an interval therebetween, and a transmittance member interposed between adjacent two partially reflecting mirrors of the plurality of partially reflecting mirrors. The transmittance member has an incidence surface on which an image light and an external light are incident through a light guiding body, and an exit surface from which the image light and the external light are exited to an observer side. Each of the plurality of partially reflecting mirrors is disposed so as to be inclined with respect to the incidence surface and the exit surface, and a reflectance of light incident at a relatively small incidence angle with respect to surfaces of each partially reflecting mirror is lower than a reflectance of light incident at a relatively large incidence angle.