An optical device includes: a light guide plate; a first light emission part provided in a first region of the light guide plate, the first light emission part having optical surfaces that cause the light incident thereon to exit from a first emission surface and a second emission surface opposite the first emission surface; and a second light emission part provided in a second region of the light guide plate, the second light emission part having optical surfaces that cause the light incident thereon to exit from the first emission surface and the second emission surface. The optical device configured to control the luminous flux from the first and second emission surfaces via the optical surfaces in the first and second light emission parts to thereby control how leaked light is perceived by an observer on the opposite side of the emission surface of the light guide plate.