A display device includes a substrate, a display unit formed on the substrate, a sealing substrate bonded to the substrate by a bonding layer surrounding the display unit, the sealing substrate comprising a complex member and an insulating member, wherein the complex member has a resin matrix and a plurality of carbon fibers and the insulator is connected to an edge of the complex member and comprises a penetration hole, a metal layer disposed at one side of the sealing substrate wherein the one side faces the substrate, and a conductive connection unit filling in the penetration hole and contacting the metal layer. The complex member and the insulator may be coupled by tongue and groove coupling along a thickness direction of the sealing substrate where the protrusion-groove coupling structure is top-to-bottom symmetric and the insulator may have a thickness identical to that of the complex member.