An etchant composition including 0.5 wt % to 20 wt % of a persulfate, 0.01 wt % to 1 wt % of a fluorine compound, 1 wt % to 10 wt % of an inorganic acid, 0.01 wt % to 2 wt % of an azole-based compound, 0.1 wt % to 5 wt % of a chlorine compound, 0.05 wt % to 3 wt % of a copper salt, 0.01 wt % to 5 wt % of an antioxidant or a salt thereof, based on a total weight of the etchant composition, and water in an amount sufficient for the total weight of the etchant composition to be equal to 100 wt % is disclosed. The etchant composition is suitable for use in forming a metal wiring by etching a metal layer including copper or in fabricating a thin film transistor substrate for a display apparatus.