The present invention provides a manufacturing method of a thin film transistor array panel, which includes forming a gate line on a substrate; forming a gate insulating layer, a semiconductor layer, and an ohmic contact on the gate line; forming a first conducting film including Mo, a second conducting film including Al, and a third conducting film including Mo on the ohmic contact; forming a first photoresist pattern on the third conducting film; etching the first, second, and third conducting films, the ohmic contact, and the semiconductor layer using the first photoresist pattern as a mask; removing the first photoresist pattern by a predetermined thickness to form a second photoresist pattern; etching the first, second, and third conducting films using the second photoresist pattern as a mask to expose a portion of the ohmic contact; and etching the exposed ohmic contact using a Cl-containing gas and a F-containing gas.