Abstract: A filtering apparatus including a filtering vessel, wherein a precoat filtering layer is formed with a filter aid on a filtering bed between a nonfiltered liquid chamber where a nonfiltered liquid to be filtered is introduced and a filtered liquid chamber; a nonfiltered liquid introduction line, including a pump and a first open/close valve connected to a suction port of the pump, for introducing the nonfiltered liquid into the nonfiltered liquid chamber; a filtered liquid outlet line, including a second open/close valve, for letting out a filtered liquid through a filtered liquid outlet port of the filtered liquid chamber; a filter aid introducing line that can be opened and closed, from a precoating liquid outlet port of the filtering vessel, via a filter aid addition part, to the pump suction port; a bypass line for precoating, from the filtered liquid outlet port of the filtering vessel to the pump suction port via a third open/close valve; and a bypass line for valve cleaning, from a liquid outlet port a