An inspection device of a display device includes a first illumination unit providing a first incident light to the display device at a first incident angle, a second illumination unit providing a second incident light to the display device at a second incident angle, a third illumination unit providing a third incident light to the display device at a third incident angle, and a defect detector receiving at least one of a first reflection light obtained from the first incident light reflected by the display device at a first reflection angle, a second reflection light obtained from the second incident light reflected by the display device at a second reflection angle, and a third reflection light obtained from the third incident light reflected by the display device at a third reflection angle to detect defects of the display device.