A display apparatus comprising: a frame to be mounted on the head of a viewer; and an image display device attached to the frame, wherein the image display device includes: an optical device including a first deflecting unit, a light guide panel configured to cause incident light to propagate therein by total reflection and to emit the light, and a second deflecting unit configured to deflect more than once light having propagated in the light guide panel and to cause said light to exit the light guide panel; an image forming device being placed on the viewer side of the light guide panel; and a thick lens facing the image forming device, with the light guide panel being interposed between the image forming device and the thick lens; wherein the image display device is configured to guide an image from the image forming device to an eye of the viewer in that the image forming device is configured to emit light through the light guide panel onto the thick lens; the thick lens is configured to reflect said light such that it reenters the light guide panel; the first deflecting unit is configured to deflect the light reflected from the thick lens such that it is totally reflected inside the light guide panel; and the second deflecting unit is configured to deflect the light deflected by the first deflecting unit toward the eye of the viewer; wherein the thick lens includes a first surface into and from which light from the image forming device is guided and emitted, and a second surface located on the opposite side from the first surface, a light reflecting layer being formed on the second surface; wherein the image forming device is nonparallel to the light guide panel and/or the thick lens is nonparallel to the light guide panel. a frame to be mounted on the head of a viewer; and an image display device attached to the frame, wherein the image display device includes: an optical device including a first deflecting unit, a light guide panel configured to cause incident light to propagate therein by total reflection and to emit the light, and a second deflecting unit configured to deflect more than once light having propagated in the light guide panel and to cause said light to exit the light guide panel; an image forming device being placed on the viewer side of the light guide panel; and a thick lens facing the image forming device, with the light guide panel being interposed between the image forming device and the thick lens; an optical device including a first deflecting unit, a light guide panel configured to cause incident light to propagate therein by total reflection and to emit the light, and a second deflecting unit configured to deflect more than once light having propagated in the light guide panel and to cause said light to exit the light guide panel; an image forming device being placed on the viewer side of the light guide panel; and a thick lens facing the image forming device, with the light guide panel being interposed between the image forming device and the thick lens; wherein the image display device is configured to guide an image from the image forming device to an eye of the viewer in that the image forming device is configured to emit light through the light guide panel onto the thick lens; the thick lens is configured to reflect said light such that it reenters the light guide panel; the first deflecting unit is configured to deflect the light reflected from the thick lens such that it is totally reflected inside the light guide panel; and the second deflecting unit is configured to deflect the light deflected by the first deflecting unit toward the eye of the viewer; the image forming device is configured to emit light through the light guide panel onto the thick lens; the thick lens is configured to reflect said light such that it reenters the light guide panel; the first deflecting unit is configured to deflect the light reflected from the thick lens such that it is totally reflected inside the light guide panel; and the second deflecting unit is configured to deflect the light deflected by the first deflecting unit toward the eye of the viewer; wherein the thick lens includes a first surface into and from which light from the image forming device is guided and emitted, and a second surface located on the opposite side from the first surface, a light reflecting layer being formed on the second surface; wherein the image forming device is nonparallel to the light guide panel and/or the thick lens is nonparallel to the light guide panel.