A display device comprising: a substrate; an encapsulation portion on the substrate; a seal portion between the substrate and the encapsulation portion; and at least one dummy seal portion adjacent to the seal portion, wherein: the substrate and the encapsulation portion at least partially overlap each other in a first direction perpendicular to a surface of the substrate; and the dummy seal portion is, when viewed in the first direction, arranged in an area between an edge of the seal portion and a boundary line of an overlapping area of the substrate and the encapsulation portion, wherein: the seal portion encompasses an active area of the substrate when viewed in the first direction; and the dummy seal portion is arranged, when viewed in the first direction, outside the active area and the seal portion, wherein, when viewed in the first direction: an area of the substrate extends beyond the boundary line; pad terminals are arranged in the area extending beyond the boundary line; signal lines are respectively connected to the pad terminals; and the signal lines cross the boundary line, wherein: the dummy seal portion is spaced apart from the seal portion when viewed in the first direction; characterized in that the dummy seal portion comprises at least one island shape. a substrate; an encapsulation portion on the substrate; a seal portion between the substrate and the encapsulation portion; and at least one dummy seal portion adjacent to the seal portion, wherein: the substrate and the encapsulation portion at least partially overlap each other in a first direction perpendicular to a surface of the substrate; and the dummy seal portion is, when viewed in the first direction, arranged in an area between an edge of the seal portion and a boundary line of an overlapping area of the substrate and the encapsulation portion, wherein: the seal portion encompasses an active area of the substrate when viewed in the first direction; and the dummy seal portion is arranged, when viewed in the first direction, outside the active area and the seal portion, the seal portion encompasses an active area of the substrate when viewed in the first direction; and the dummy seal portion is arranged, when viewed in the first direction, outside the active area and the seal portion, wherein, when viewed in the first direction: an area of the substrate extends beyond the boundary line; pad terminals are arranged in the area extending beyond the boundary line; signal lines are respectively connected to the pad terminals; and the signal lines cross the boundary line, wherein: the dummy seal portion is spaced apart from the seal portion when viewed in the first direction; characterized in that the dummy seal portion comprises at least one island shape. an area of the substrate extends beyond the boundary line; pad terminals are arranged in the area extending beyond the boundary line; signal lines are respectively connected to the pad terminals; and the signal lines cross the boundary line, wherein: the dummy seal portion is spaced apart from the seal portion when viewed in the first direction; characterized in that the dummy seal portion comprises at least one island shape. the dummy seal portion is spaced apart from the seal portion when viewed in the first direction; characterized in that the dummy seal portion comprises at least one island shape.