A filtration filter used for filtering a liquid chemical for lithography, provided with a polyimide resin porous membrane; a filtration method including allowing a liquid chemical for lithography to pass through the filtration filter; and a production method of a purified liquid chemical product for lithography, including filtering a liquid chemical for lithography by the filtration method.

The present disclosure relates to a membrane having uniform pore size and pore arrangement. The present disclosure provides a membrane including a plurality of pores, wherein the diameter of the plurality of pores is 100 m or less, the porosity is 20 to 80%, the thickness is 3 to 500 m, and the membrane is a single layer membrane.