An illumination device (100) includes at least one light source (20), a receiving seat (10) and a power source (40) arranged on the receiving seat (10) for supplying currents to the at least one light source (20). The receiving seat (10) includes a panel (12) and a back plate (14) assembled to the panel. At least one receiving chamber (16) is defined between the panel (12) and the back plate (14). The receiving chamber (16) defines an opening at a lateral side of the receiving seat (10). The at least one light source (20) is mounted into the at least one receiving chamber (16) via the opening. A block (141a) extends outwardly from the back plate (14) to the opening of the receiving chamber (16) to prevent the at least one light source (20) from falling out from the at least one receiving chamber (16) of the receiving seat (10).
