A display device including: a display panel; and an input sensor disposed on the display panel, wherein the input sensor includes: sensing electrodes; signal lines connected to the sensing electrodes; a first insulating layer; a second insulating layer disposed on the first insulating layer; and first, second and third test patterns having different stacking structures from each other, wherein the first test pattern include a first conductive pattern, a first insulating pattern overlapping the first conductive pattern, and a second insulating pattern overlapping the first insulating pattern, the second test pattern includes a third insulating pattern and a fourth insulating pattern overlapping the third insulating pattern, and

the third test pattern includes a second conductive pattern.