1. A binocular image display apparatus provided which comprises: two image display devices corresponding to the left and right eyeballs of a viewer, respectively, and two viewing optical systems, one for the left eye and one for the right eye, for projecting original images on the image display devices onto the left and right eyeballs of the viewer, wherein: in the left-eye and right-eye viewing optical systems, an observation image projected onto one eyeball includes a fused image area wherein the observation image overlaps a part of an observation image projected onto another eyeball and a monocular area other than the fused image area, and inside resolution in a horizontal direction with respect to a visual axis of the viewer is set higher than outside resolution.