A display device including a substrate, first and second reference voltage lines, a first insulation layer is provided. The first and second reference voltage lines are disposed in a peripheral area of the substrate. The first insulation layer having a groove is disposed on the first reference voltage line. The groove extends along a first direction and exposes a contact portion of the first reference voltage line. The first insulation layer covers a first covered portion of the first reference voltage line. The second reference voltage line contacts the contact portion at the groove and has a contact surface. In a second direction, a first width W1 of the contact surface, a second width W2 of the first reference voltage line and a third width W3 of the first covered portion are complied with 1 μm≤W1≤(W2−W3), wherein than 0 and smaller than W2.