In a light-emitting element provided with a thick layer of a plurality of EL layers which are partitioned by a charge generation layer between a pair of electrodes, a portion which a conductive foreign substance enters between the pair of electrodes emits stronger light at a voltage lower than a voltage required when a normal portion starts emitting light. In a light-emitting element provided with a plurality of EL layers which are partitioned by a charge generation layer between a pair of electrodes, a voltage may be applied thereto in the forward direction. Then, an abnormal light-emission portion may be detected because the portion emits light at a luminance of 1 (cd/m2) or higher when the applied voltage is lower than a voltage required when a normal portion starts emitting light. The portion may be irradiated with laser light so as to be insulated.