Cabin illumination device

A cabin illumination device is provided on a wall surface of a cabin of a vehicle and illuminates the cabin and includes: a light source disposed to emit light away from the wall surface; and a reflective member disposed to intersect a light axis of light emitted by the light source. The reflective member includes a first protruded surface disposed to intersect the light axis of the light source, and a portion of the reflective member is sloped downward in a direction away from an intersection of the light axis and the first protruded surface.