An illumination device is disclosed that may constitute a partition wall or the like having an impact in a bright and brilliant space. An illumination device according to an embodiment may include: a plurality of light guide plate units each including a light guide plate and an LED substrate; and a base to which the plurality of light guide plate units are attached so as to be laid over the base. The attachment surface of the base is divided into sections for attaching the light guide plate units so as to lay the light guide plate units over the base and each section is provided with an IC board for driving the corresponding LED substrate and snap-fit engagement portions for fixing the light guide plate unit to the base.