In an organic electroluminescent (EL) display device, a main display panel and a sub display panel share a data line and a power supply voltage line. The organic EL display device has a top emission type main display panel and a bottom emission type sub display panel in a single display panel. The main display panel is composed of main pixels, each having a compensation circuit for compensating a threshold voltage, and the sub pixel display is composed of basic sub pixels without any compensation circuit. Each of the sub pixels has a boost capacitor which increases a data voltage, and which is disposed between a scan line and a storage capacitor so as to use the same voltage and power supply voltage as the main pixels. The sub pixels having the boost capacitor are disposed in the sub display panel, so that the main and sub display panels share the data line and the power supply voltage line.