The present invention relates to an organic electroluminescent device and a driving method thereof. The organic electroluminescent device according to the present invention comprises a plurality of scan lines in a first direction, a plurality of data lines in a second direction different from the first direction, a panel having a plurality of pixels formed on crossing areas of data lines and scan lines, and a data driving circuit which drives the pixels according to a display data and a brightness control data inputted from external apparatuses. The data driving circuit comprises a display data recognizing circuit which receives display data from a first external apparatus in the external apparatuses and a current generating circuit which receives brightness control data from a second external apparatus in the external apparatuses, and applies a data current according to the display data recognized in the display data recognizing circuit and the brightness control data to the data lines.