ILLUMINATION DEVICE

An illumination device is to be mounted on a ceiling of an interior of a vehicle, and the illumination device includes a light source that emits light to illuminate the interior, a light guide that receives the light emitted from the light source and transmits the received light, a first flow path that, in a state in which the illumination device is mounted on the ceiling, extends so as to intersect with an up and down direction of the vehicle and is located at the same position as at least one of the light source or the light guide in the up and down direction, and an air blower that produces an airflow that, having been sucked into the illumination device, travels through the first flow path and is blown out of the illumination device after having traveled through the first flow path.