Disclosed is a hub ring for a filter wherein a supporting member having a plurality of supporting portions is interposed between a pair of keep plates, a supporting plate for a filter wherein a plurality of wave portions extending substantially in the circumferential direction are arranged in the radial direction, and methods for manufacturing these members. The hub ring has a great opening ratio to achieve a low pressure loss property and causes substantially no residence of polymer, and the hub ring can be manufactured at a low cost. The supporting plate has high pressure resistance, low-pressure loss property, good directivity of polymer flow and excellent polymer mixing effect, and it is suitable for use as a retainer disposed inside of a filter.