A method of manufacturing a thin film transistor array panel is provided, which includes: forming a gate line on a substrate; depositing a gate insulating layer and a semiconductor layer in sequence on the gate line; depositing a lower conductive film and an upper conductive film on the semiconductor layer; photo-etching the upper conductive film, the lower conductive film, and the semiconductor layer; depositing a passivation layer; photo-etching the passivation layer to expose first and second portions of the upper conductive film; removing the first and the second portions of the upper conductive film to expose first and second portions of the lower conductive film; forming a pixel electrode on the first portion of the lower conductive film; removing the second portion of the lower conductive film to expose a portion of the semiconductor layer; and forming a columnar spacer on the exposed portion of the semiconductor layer.