An etching apparatus for substrates includes an etching tank including an etching solution, a cassette having a plurality of substrates mounted therein and which is installed inside the etching tank, a porous plate installed on a lower surface of the cassette and a plurality of discharge sections provided in the porous plate corresponding to the substrates and each of the discharge sections having a plurality of discharge ports. The etching apparatus further includes a plurality of first lines connected to the discharge ports respectively, and supplied with a gas to provide bubbles to the substrates through the discharge ports. The first lines are divided into a plurality of groups, and at least one group is supplied with a gas having a pressure different from a pressure of a gas supplied to other groups.