Abstract: A filter retainer supports filtering materials on both surfaces of the filter retainer. A pair of etched circular plates having a large number of circumferentially arranged through-holes formed by chemical etching are joined to each other at a condition where the positions of corresponding through-holes are aligned to coincide with each other, and at the joined form, radially extending internal paths are formed between the pair of etched circular plates. The structure of the filter retainer avoids accuracy and pressure loss of conventional filter elements cause by internal structures thereof.