A display device includes: a first substrate; a gate electrode on the first substrate; a gate insulating layer on the gate electrode; a semiconductor layer on the gate insulating layer; a source electrode and a drain electrode spaced apart from each other on the semiconductor layer; a first passivation layer including a silicon nitride-based material and on the semiconductor layer, the source electrode, and the drain electrode; a second passivation layer including a silicon nitride-based material and on the first passivation layer; and a third passivation layer including a silicon nitride-based material and on the second passivation layer, where a content ratio of silicon in the first passivation layer is higher than a content ratio of silicon in the second passivation layer, and the content ratio of silicon in the second passivation layer is higher than a content ratio of silicon in the third passivation layer.