The apparatus for producing a non-aqueous electrolytic solution includes: a moisture adsorption apparatus accommodating zeolite through which an organic non-aqueous solvent passes, an electrolyte addition apparatus for adding an alkali metal salt electrolyte to the organic non-aqueous solvent treated by the moisture adsorption apparatus, and an acid adsorption apparatus accommodating a weakly basic anion exchange resin through which an alkali metal salt electrolyte-containing solution obtained by the electrolyte addition apparatus passes.

An affinity support having improved binding capacity for target proteins. An immunoglobulin-binding protein including a mutant immunoglobulin-binding domain, an affinity support including a solid-phase support and the immunoglobulin-binding protein immobilized thereto. The mutant immunoglobulin-binding domain consists of an amino acid sequence having at least 85% identity with an amino acid sequence of any of SEQ ID NOs: 1 to 12.