Poly(gamma-glutamic acid) (PGA) was successfully electrospun by the addition of poly(ethylene glycol) (PEG) and Triton X-100 in its aqueous solution to produce the PGA non-woven mat of the ultrafine fibers. The average fiber diameter was in the range between 200 nm and 2 mu m. The fiber mat was quickly soluble in water due to the large surface area of the fibers. The electrospinning of PGA butyl ester with the esterification degree of 61% in 1,1,1,3,3,3-hexafluoro-2-propanol gave the water-insoluble nanofiber mat.