To surely remove impurities contained through processing, without reducing a circulation efficiency, as for a processing liquid reused with circulation.

As for the circulating system for applying eluate delivered from spray pipes 72 and 74 on a printing plate 12, storing the surplus in an eluate tank 40 and then reusing the eluate, a filter unit 156 having a priority of the removal of the impurities is arranged above the eluate tank 40. Since a large area for receiving the eluate can be given to the filter unit 156, the circulation efficiency is not drastically influenced even in the case the passing ratio of the eluate is slightly reduced due to the installation of a fine mesh filter. Even in the case the passing ratio is reduced by the clogging of the filter main body 158 due to aging, the eluate is prevented from flowing into the eluate tank 40 without passing through the filter main body 158, because the vertical wall part 168 and an eluate remaining area are arranged.