A flux of light entering a transparent medium L2 proceeds along a side view optical path A by way of the first transmissive surface 21 so as to be reflected to the side opposite to the image plane by the first reflective surface 22 and then to the image plane side by the second reflective surface 23 to form a substantially Z-shaped optical path before going out from the transparent medium L2 to the outside at the image plane 5 side by way of the second transmissive surface 24 in the order of forward ray tracing and also along a direct view optical path B by way of third transmissive surface 25 to form another optical path before going out from the transparent medium L2 into the outside at the image plane 5 side by way of the fourth transmissive surface 26 also as viewed in the order of forward ray tracing.
