According to one embodiment, an illumination device includes a light guide including an upper surface, a lower surface and a light entering surface, a first light emitting portion, a second light emitting portion, and a third light emitting portion. A first surface, a second surface, a third surface and a fourth surface of the upper surface are arranged in this order in a first direction. A width of the first surface is less than a width of the second surface, and the width of the second surface is less than a width of the third surface. An angle between the light entering surface and the first surface is an acute angle. The first light emitting portion, the second light emitting portion and the third light emitting portion face the light entering surface.