The present invention provides a method for producing a separator for nonaqueous electrolyte electricity storage devices. The method allows: avoidance of use of a solvent that places a large load on the environment; relatively easy control of parameters such as the porosity and the pore diameter; and a high electrochemical stability of a resultant separator for nonaqueous electrolyte electricity storage devices. The present invention relates to a method for producing a separator for nonaqueous electrolyte electricity storage devices that has a thickness ranging from 5 to 50 μm. The method of the present invention includes the steps of: preparing an epoxy resin composition containing an epoxy resin whose molecular structure has no aromatic ring, a curing agent, and a porogen; forming a cured product of the epoxy resin composition into a sheet shape or curing a sheet-shaped formed body of the epoxy resin composition, so as to obtain an epoxy resin sheet; and removing the porogen from the epoxy resin sheet by means of a halogen-free solvent.