Abstract: Provided is a filtration device including: a flow path that meanders; a filtration membrane that separates a supply side and a permeation side of the flow path; a first distribution port that is provided at one end of the supply side of the flow path; a second distribution port that is provided at the other end of the supply side of the flow path; a first discharge port that is provided on the permeation side of the flow path; and a second discharge port that is provided at a position different from that of the first discharge port on the permeation side of the flow path. First liquid feeding for allowing a liquid flowed in from the first distribution port to flow out from the second distribution port, and second liquid feeding for allowing a liquid flowed in from the second distribution port to flow out from the first distribution port are alternately performed.