<p>A filtration device (50) that has a large number of filters (52) each composed of a filter element and a casing. In the filtration device (50), filter strings (82) are constructed from the filters (52) parallelly connected by header tubes (58) such as unfiltered liquid feeding header tubes (60), filtrate recovery header tubes (62), and unfiltered liquid recovery header tubes (64). At least two rows of filter strings (82) are parallelly connected by a filtrate recovery collecting tube (84). Also, the filtrate recovery collecting tube (84) is placed at a higher position than the filtrate recovery header tubes (62).</p>
