The invention relates to an improvement of the construction of filter plates. The filter plates comprise a frame, flat filtrate drainage guide means disposed in the frame, and supporting means for movably supporting the filtrate drainage guide means in the frame. The filtrate drainage guide means of such construction can be prevented from being broken if filtration pressure applied to one face of the filtrate drainage guide means of the filter plate is much different from that applied to the other face of the filtrate drainage guide means because the filtrate drainage guide means can be movably provided in the frame. |