A light emitting element has a property that a resistance value (internal resistance value) thereof changes according to the ambient temperature. Specifically, assuming that the room temperature is a normal temperature, when the ambient temperature becomes higher than the normal temperature, a resistance value is decreased, and when the ambient temperature becomes lower than the normal temperature, a resistance value is increased. Therefore, when the ambient temperature changes or degradation is caused with time due to the aforementioned property of the light emitting element, luminance varies. The invention provides a display device where an effect of current fluctuation of a light emitting element, which is caused by the change in ambient temperature and degradation with time, is suppressed. The display device comprises a monitoring element, to which a current is supplied from a current source. A voltage applied to the monitoring element is applied to a light emitting element.