To feed a constant volume of chemical liquid by completely excluding air bubbles in a filter apparatus, in which a constant volume of chemical liquid is introduced, filtered, and fed to other apparatus.

A valve disc 7, that closes a discharge opening for discharging chemical liquid containing air bubbles and remains in the filter apparatus, is provided. A valve seat 9 of the discharge opening is closed after the remaining chemical liquid with air bubbles is pushed out to the outside through the discharge pipe 5 in advance, and the chemical liquid in the housing 2 free of compressive air bubbles is sent out at a constant pressure.