An illuminating device includes a light source body and a lens array. The light source body includes a plurality of light sources. The lens array includes an opposed surface, a reverse surface, a plurality of lenses, a recess, and a projection. The plurality of lenses corresponds respectively to the plurality of light sources. The plurality of lenses includes a first lens and a second lens, which is located adjacent to the first lens. The recess is formed at an end portion of the first lens adjacent to the second lens. The projection is formed at an end portion of the second lens adjacent to the first lens. The projection is coupled with the recess, so that at least a part of a boundary line between the first lens and the second lens is formed in a concave-convex shape as a result of a combination of the recess and the projection.