According to one embodiment, a method of manufacturing a display device, includes forming a lower electrode on a base, forming a rib which covers a part of the lower electrode, forming a partition including a lower portion disposed on the rib and an upper portion protruding from a side surface of the lower portion, removing the upper portion of at least a part of the partition, measuring a first width of the lower portion of the partition and a second width of the upper portion of the partition and measuring a distance between the side surface of the lower portion and an end portion of the upper portion based on the first and second widths.