A method of manufacturing a perforated porous resin substrate, the method including the following steps: Step 1 of forming at least one perforation penetrating in the thickness direction from a first surface to a second surface in a porous resin substrate made of a resin material containing a fluoropolymer; Step 2 of etching treatment conducted by putting an etchant containing an alkali metal in contact with the wall face of each perforation; and Step 3 of putting an oxidizable compound or a solution thereof in contact with a degenerative layer generated by the etching treatment, and thereby removing the degenerative layer. A method of manufacturing a porous resin substrate in which electrical conductivity is afforded to the wall face of the perforation.