An organic electroluminescent device comprising: a transparent support substrate having flexibility; a light emitting element disposed on the transparent support substrate and including a pair of electrodes and a luminescent layer disposed between the pair of electrodes; a sealing material layer disposed on the transparent support substrate so as to cover and seal the light emitting element; and a sealing substrate disposed on the sealing material layer, wherein based on an arithmetic average of roughness profile defined in JIS B 0601-1994, the surface roughness of a surface of the sealing substrate beside the sealing material layer has a smaller value than the surface roughness of the other surface of the sealing substrate, and the arithmetic average of roughness profile of the surface of the sealing substrate beside the sealing material layer and a thickness of the sealing material layer satisfy a requirement represented by the following formula (I): 0.002