An array substrate for an LCD includes a substrate, a gate line, a data line, a gate electrode extending from the gate line formed on the substrate, a gate insulating layer covering the gate electrode and the substrate, a semiconductor layer formed over the gate insulating layer, a source electrode formed on the semiconductor layer extending from the data line, a drain electrode formed on the semiconductor layer facing the source electrode, a passivation layer covering the substrate including a resultant structure obtained after the source electrode and the drain electrode are formed, and a pixel electrode contacting the drain electrode through a contact hole passing through the passivation layer, wherein a portion of the gate insulating layer in a region where the gate electrode is formed is thinner than a portion of the gate insulating layer in a region where the gate line and the data line intersect with each other.