The solution film-forming method is provided in which the absolute filtration accuracy for a cellulose acylat solution can be improved and filtration throughput can be increased without reducing the pore size of a filtering material. A dope stock solution to be filtrated is first introduced into a body feed tank and a filter aid from a filter aid tank is added and dispersed. As the filter aid, an aid including SiO2 in 50% or more and a cellulose-based aid are mixed for use. The dope stock solution in which the filter aid is dispersed is introduced into a filter machine and subjected to filtration while forming a cake on the surface of the filtering material. After the filtration, a cleaning solvent is supplied in circulation from a cleaning solvent tank, and the cake is discharged as slurry. The filter aid is separated from the slurry by a separating device and burned in a burning device. Then, a regenerated filter aid is sent to the filter aid tank. After the cleaning, a precoat liquid in which the filter aid is dispersed is supplied from a precoat tank to the filter machine to form a precoat layer on the surface of the filtering material.