A method ensuring excellent chemical resistance to a chemical cleaning solution, excellent filtration performance and an enhanced life in a saccharified solution production method including a cleaning step and filtration using a porous filtration membrane. A method for producing a saccharified solution, including the following steps: a liquefaction step of adding an enzyme to liquid starch to obtain a sugar-containing liquefied product; a saccharification step of adding a saccharifying enzyme to further degrade the sugar and obtain a saccharified solution composition containing a saccharified solution and an insoluble component; a filtration step of passing the saccharified solution composition through a porous membrane composed of a resin having a three-dimensional network structure to separate the saccharified solution from the insoluble component; and a cleaning step of passing or soaking the porous membrane into a cleaning solution to clean/remove the insoluble matter attached to the surface or inside of the porous membrane.