According to an embodiment, a semiconductor light emitting device includes a light emitting body including a semiconductor light emitting layer, a support substrate supporting the light emitting body, and a bonding layer provided between the light emitting body and the support substrate, the bonding layer bonding the light emitting body and the support substrate together. The independently detachable light-emitting diode light source module includes an installing device, a light-emitting diode array, and a secondary optical light guide plate. The pull-down circuit 2 includes a resistive element R4 and a P-type transistor Tr4 which are connected in series.