The present invention relates to a cell preparation method that includes a step in which cells are applied to a polyimide porous film and cultivated, wherein the polyimide porous film is a polyimide porous film with a three-layer structure, having a surface layer A and a surface layer B that have a plurality of holes, and a macrovoid layer that is sandwiched between the surface layer A and the surface layer B, and the polyimide porous film is produced by a method including the following steps: (1) a step in which a poly(amic acid) solution comprising poly(amic acid) and an organic polar solvent is flow cast in a film shape and the result is immersed in or brought into contact with a coagulation medium to create a porous film of poly(amic acid); and (2) a step in which the porous film of poly(amic acid) obtained in step (1) is heat-treated and imidized.