A light guide device includes a light guide plate that includes a first surface and a second surface facing the first surface in one of which plural light exit portions are provided, that guides light introduced into the light guide plate while reflecting the light between the first surface and the second surface, and that refracts or reflects the guided light so as to cause the light to exit by using the plural light exit portions. The light guide device has an introduction portion that is provided in the light guide plate and that introduces at least part of light incident upon the introduction portion in plural directions in a plane where the light is guided by the light guide plate.