An organic electroluminescent device comprising a supporting substrate, a sealing substrate and an organic electroluminescent element, comprising: the organic electroluminescent element mounted on the supporting substrate, and enclosed between the supporting substrate and the sealing substrate, and an insulating layer that covers the organic electroluminescent element, wherein the supporting substrate and/or the sealing substrate adhered to the insulating layer is formed of a material having thermal conductivity of 2 W/m·K or more, and wherein one surface of the supporting substrate and/or the sealing substrate formed of the material having the thermal conductivity, which is the surface constituting an exterior of the organic electroluminescent device, has surface roughness (Ra value) of 10 nm or more and 1 mm or less.