Filter membrane cleaning apparatus, filter membrane cleaning method, and water treatment system

This invention provides a filter membrane cleaning apparatus including an ozone water generating tank (12), in which ozone gas is dissolved in water to generate ozone water, and the generated ozone water and exhaust ozone gas that is the by-products are accumulated; a reverse cleaning mechanism, which performs reverse cleaning for a filtering membrane (51) with the stored ozone water with respect to a filtering unit (5) for filtering raw water; a membrane surface cleaning mechanism, which releases bubbles containing ozone in the biological reaction tank (4), and performs membrane surface cleaning for the filter membrane (51); a control unit (30), which controls the actions of the reverse cleaning mechanism and the membrane surface cleaning mechanism so that the membrane surface cleaning by the membrane surface cleaning mechanism is performed before the reverse cleaning by the reverse cleaning mechanism; and an exhaust ozone gas dilution unit, which dilutes the accumulated exhaust ozone gas and supplies it to