Disclosed are a filtering system and a filtering method which minimize the contamination of a filtering membrane through a pretreatment process, and which enable the pretreatment process and a filtering process to be performed using the filtering membrane and by a single filtering unit, thus eliminating the necessity of a separate space and facility for pretreatment. The filtering system of the present invention includes a microbubble supply unit which supplies microbubbles to water. The water to be treated by a dynamic filtering layer formed in the filtering unit is supplied to the filtering unit by means of the flotation of the microbubbles so as to carry out the pretreatment.
