Provided is an operation method for a coating exhaust treatment system that includes a filter configured to filter discharged air discharged from a coating chamber in which a coating object is spray-coated and collect overspray coating material included in the discharged air, and a powder dispersal means configured to disperse powder for forming a filter covering layer in the discharged air and form a filter covering layer made of a layer of the accumulated powder on a surface on the filter as the discharged air passes through the filter, the method including, when the number of repetitions of a first operation reaches a set number while the first operation and a second operation are being repeatedly carried out alternatingly, discarding coating material-containing powder and supplying fresh powder to a first supply tank, and when the number of repetitions of the second operation reaches the set number, discarding the coating material-containing powder and supplying the fresh powder to the second supply tank.