VEHICULAR INTERIOR LIGHTING DEVICE AND ROOF MODULE

A vehicular interior lighting device includes a main body portion fixed to an inside surface of a roof, a light source accommodated in the main body portion, a light shielding cover portion constituting a housing with the main body portion and covering the light source from below, and a light guide member having a protruding portion protruding along the inside surface from a gap between the main body portion and the cover portion. The light guide member has a diffusion portion formed on a surface of the protruding portion facing downward and diffusing light, a first light guide portion guiding light emitted from the light source to the protruding portion, and a reflecting portion reflecting light guided by the first light guide portion toward the diffusion portion.