A vehicle light and a road illumination device can include a semiconductor light emitting device capable of forming a luminance distribution where the light with a maximum value can be arranged at or near a light distribution cutoff line, thereby improving its light utilization efficiency. The vehicle light can include a semiconductor light emitting device including a semiconductor light emitting element and a wavelength conversion layer having a thickness-decreased portion that is formed substantially at a center line of the semiconductor light emitting element and extending to one end thereof so that the thickness is reduced from the center portion toward the one end. A projection optical system for forming a cutoff line can be configured to project a plurality of light source images each including an image portion corresponding to the thickness-decreased portion at its upper area, and to arrange the image portions in at least one of a horizontal direction and an oblique direction.