The present invention relates to a method for preparing a porous polymer film having a controlled pore depth, and a porous polymer film prepared thereby. A method for preparing a porous polymer film according to the present invention allows the pore depth of a porous film to be controlled simply and at a low cost, and thus allows adjustment of the light reflectance of the prepared film. A large-area film can be prepared by means of a simple method and thus can be applied to various industry fields. Films having different reflectance can be prepared and thus can be applied as low-reflection and high-reflection films for solar cells, and also as a low-reflection or high-reflection thin polymer film in the construction field or material and equipment field.

A liquid composition which enables formation of a membrane with high designability suitable to be provided to a variety of industrial products, such as electronic devices and electronic device components, is provided. Here, (A) indicates a resin component, (B) unevenness forming particles, (B1) inorganic small particles having a particle diameter (d.sub.1) of 0.05 m or more and 0.4 m or less, (B2) inorganic-type large particles having a particle diameter (d.sub.2) of 2 m or more and 6 m or less, and (C) a diluent solvent. The liquid composition is for forming a membrane by spray coating and comprises at least (A), (B) and (C). The (B) is contained in an amount of 20% by mass or more and 60% by mass or less in 100% by mass of a total amount of the total solid content in the composition. The (B) contains (B1) and (B2) in an amount of 90% by mass or more. A mass ratio of (B2) to (B1):1 is 1.8 or more and 3.3 or less.