A method is provided for producing a separator by cutting a laminated porous film. The laminated porous film includes a porous base material layer containing polyolefin as a main component and a filler layer containing inorganic particles as a main component. The filler layer is provided on one surface of the porous base material layer; and a resin layer containing resin particles as a main component is provided on the other surface of the porous base material layer. The method includes a step of cutting, using a slit blade, the laminated porous film from the one surface on which the filler layer is provided.