Poly-gamma-glutamic acid (gamma-PGA) is a water-soluble, nontoxic biodegradable polymer. It is extensively utilized in medicines, foodstuffs, and cosmetics, as well as in water treatment. Highly pure gamma-PGA is required for various purposes. In many cases, gamma-PGA is produced by microbes of Bacillus sp. However, an increase in the viscosity of the culture broth is one of the major problems of gamma-PGA production, as higher viscosity makes the separation and purification steps difficult. Herein, we propose a novel method to obtain pure gamma-PGA using gemini quaternary ammonium salts (GQASs). The quaternary ammonium cation of GQASs binds to the carboxylic acid group of gamma-PGA via an ionic bond, following which waterinsoluble and antimicrobial complexes are formed. These complexes are obtained in the aqueous solution, which were resolved in ethanol solution. With an increase in the added amount of GQAS, the negative charge of the complex decreased in the aqueous solution. Subsequently, the GQAS within the complexes was dissociated by the addition of NaCl, affording pure gamma-PGA in a high yield. Moreover, the complexes were shown to have antibacterial activity and adhered to glass, indicating that the complex itself has a utility value.