An apparatus for etching a substrate includes (a) a nozzle system including at least one nozzle through which acid solution containing at least hydrofluoric acid is sprayed onto the substrate, (b) a mover which moves at least one of the nozzle system and the substrate relative to the other in a predetermined direction in such a condition that the substrate and the nozzle system face each other, (c) a filter system which filters off particles out of the acid solution having been sprayed onto the substrate, and (d) a circulation system which circulates the acid solution having been sprayed onto the substrate, to the filter system, and further, to the nozzle system from the filter system.