To provide a method for simply removing the precipitate on the surface of a web impossible to correspond to the mere removal of foreign matter, and an apparatus therefor.

First and second pass rolls 30a and 30b are provided to the feed route of a PS plate 11. The precipitate on the surface of the plate 11 is collected by the respective pass rolls 30a and 30b, and the precipitate bonded to the respective pass rolls 30a and 30b are collected by a cleaning fabric 36. The cleaning fabric 36 is supplied from a supply spool 39 at each time when the PS plate 11 is fed over a predetermined distance and taken up by a winding spool 41. The new unused surface of the cleaning fabric 36 is sent to the contact parts of the respective pass rolls 30a and 30b and a cleaning roll 40. The re-transfer of the precipitate to the PS plate 11 from the respective pass rolls 30a and 30b is prevented.