An etching apparatus is provided for etching a substrate. The etching apparatus includes a first tank including a first etchant, and an etch bath connected to the first tank and receiving the first etchant, the etch bath containing a residual etchant including a diluted etchant and residue material after the substrate is etched with the first etchant. The etching apparatus further includes a second tank receiving the residual etchant from the etch bath and separating the diluted etchant from the residue material, a connecting passage connecting the first and second tanks for transferring the separated diluted etchant from the second tank to the first tank, and an outlet pipe attached to the second tank for discharging the residue material.