A method for manufacturing a second brewed alcoholic beverage and washing a porous membrane used in the manufacturing, comprising: a filtration step for passing a first brewed alcoholic beverage, which contains a yeast and a high-molecular substance or sediment component produced through fermentation by the yeast, through a porous hollow fiber membrane, which is formed of a resin having a three-dimensional network structure, to thereby separate a second brewed alcoholic beverage from the yeast; and a washing step for passing a washing solution through the porous membrane or immersing the porous membrane in the washing solution to thereby wash the inside of the porous membrane; wherein, in an SEM image of a cross section along the membrane thickness direction of the porous membrane perpendicular to the inside surface of the porous membrane, in each region of a total 4 views: a view comprising the inside surface, a view comprising an outside surface of the membrane, and two views photographed at equal intervals therebetween, the total sum of the areas of resin parts with an area of 1 μm 2 or less, determined as described in " Electron microscopy" in the description, amounts to 70% or more relative to the overall area of resin parts, the sum total of the areas of resin parts with an area of more than 1 μm 2, determined as described in " Electron microscopy" in the description, is 2% or more and 30% or less relative to the total area of resin parts; the washing solution is an aqueous solution containing 0.01 wt% to 0.5 wt% of sodium hypochlorite, or 0.1 wt% to 1 wt% of a peroxide; the resin composing the porous membrane is a thermoplastic fluororesin; and in the washing step, the yeast attached to the porous membrane, and a high-molecular substance selected from the group of proteins, polysaccharides, and complexes thereof, or a sediment component contained in the first brewed alcoholic beverage, which is a substance made by complexing a protein, a polyphenol and/or a tannin via fermentation, are removed. a filtration step for passing a first brewed alcoholic beverage, which contains a yeast and a high-molecular substance or sediment component produced through fermentation by the yeast, through a porous hollow fiber membrane, which is formed of a resin having a three-dimensional network structure, to thereby separate a second brewed alcoholic beverage from the yeast; and a washing step for passing a washing solution through the porous membrane or immersing the porous membrane in the washing solution to thereby wash the inside of the porous membrane; wherein, in an SEM image of a cross section along the membrane thickness direction of the porous membrane perpendicular to the inside surface of the porous membrane, in each region of a total 4 views: a view comprising the inside surface, a view comprising an outside surface of the membrane, and two views photographed at equal intervals therebetween, the total sum of the areas of resin parts with an area of 1 μm 2 or less, determined as described in " Electron microscopy" in the description, amounts to 70% or more relative to the overall area of resin parts, the sum total of the areas of resin parts with an area of more than 1 μm 2, determined as described in " Electron microscopy" in the description, is 2% or more and 30% or less relative to the total area of resin parts; the washing solution is an aqueous solution containing 0.01 wt% to 0.5 wt% of sodium hypochlorite, or 0.1 wt% to 1 wt% of a peroxide; the resin composing the porous membrane is a thermoplastic fluororesin; and in the washing step, the yeast attached to the porous membrane, and a high-molecular substance selected from the group of proteins, polysaccharides, and complexes thereof, or a sediment component contained in the first brewed alcoholic beverage, which is a substance made by complexing a protein, a polyphenol and/or a tannin via fermentation, are removed.