A method of manufacturing a thin film transistor array panel is provided, which includes: forming a gate line on a substrate; forming a gate insulating layer on the gate line; forming a semiconductor layer on the gate insulating layer; forming an ohmic contact on the semiconductor layer; forming a data line and a drain electrode on the ohmic contact; depositing a passivation layer on the data line and the drain electrode; forming a first photoresist layer on the passivation layer; etching the passivation layer and the gate insulating layer using the first photoresist layer as a mask to expose a portion of the drain electrode and a portion of the substrate; depositing a conductive film; and removing the photoresist layer; to form a pixel electrode on a portion of the drain electrode exposed by the etching of the passivation layer.