According to one embodiment, an illumination device including a light source unit including a light-emitting element having a light-emitting surface, a reflective surface formed around the light-emitting surface and having higher optical reflectivity than the light-emitting surface, a wavelength conversion member which converts a wavelength of emitted light from the light-emitting surface, an optical member located between the light source unit and the wavelength conversion member and including a light path adjustment mechanism which guides, to the reflective surface, light returned from the wavelength conversion member to the light-emitting surface, and a lightguide opposed to the wavelength conversion member.