PURPOSE: To remarkably enhance operation efficiency, by fully automating the washing of the filter cloth of a suspension filter cloth type filter press.

CONSTITUTION: When filter plates 6, 6' of a filter press are opened and filter cloth 15 is developed in an inverted V-shape, a ceiling travelling girder 25 is moved to the developed position. When the limit switch L1 of said girder 25 is contacted with the extended part of the filter cloth suspending bar 14, said girder 25 is stopped. A horizontally running truck 26 and a lift table 33 are moved to mount a washing apparatus 35 to the lower end position within the forming space of the filter cloth 15. At this position, nozzle bars 36 move to a direction for enlarging intervals therebetween and are stopped when a limit switch L5 is contacted with the filter cloth 15. The nozzle bars 36 rise and fall while high pressure water is injected from the nozzles 36a thereof to wash the filter cloth 15. In this case, the nozzle bar intervals are controlled by a nozzle bar interval control mechanism 38.