An automotive illumination device includes a dome lamp bulb, a transistor switch, an in-vehicle unit, a door status detection unit, and a microcontroller. When user's access to an automobile has been detected by the in-vehicle unit, the microcontroller controls ON/OFF operation of the transistor switch at duty ratio of 60 percent to turn on the dome lamp bulb at brightness of 60 percent (welcome illumination state or mode). When opening of a door of the automobile has been detected by the door status detection unit during the welcome illumination, the microcontroller controls the ON/OFF operation of the transistor switch to always close the transistor switch (at duty ratio of 100 percent) to illuminate the dome lamp bulb at brightness of 100 percent.