Provided is an illumination device including a light source, a power supply to supply power to the light source, a housing including one side formed to be open, and including the light source and the power supply in the housing, at least one diffusion cover, disposed on the open side of the housing, through which light from the light source passes, and a power cover, disposed on the open side of the housing, to cover one side of the power supply. The illumination device may minimize a number of components or tools used for installing the illumination device. The illumination device may be readily installed by changing a structure and components included in the illumination device may be readily changed and repaired.