An illumination device according to an embodiment includes a light emitting element, a light distribution control unit and a light diffuser. The light distribution control unit is arranged at an emission direction side of light of the light emitting element. The light diffuser is arranged at an advancing direction side of the light relative to the light distribution control unit, in which each of a plurality of rows of convex portions having biaxial anisotropy in a plan view extends in a predetermined anisotropic axis direction, in which the plurality of rows is arranged orthogonal to the predetermined anisotropic axis and has grooves of irregular depths between the arranged plurality of rows of the convex portions.