A method for producing a durable electron-emitting device having a uniform electron emission characteristic, an electron source, and an image-forming apparatus having a uniform display characteristic for a long period are provided. The method for producing an electron-emitting device according to the present invention includes the steps of: disposing a cathode electrode on a surface of a substrate; providing an electrode opposite the cathode electrode; disposing plural pieces of fiber containing carbon as a main component on the cathode electrode; and applying potential higher than potential applied to the cathode electrode under depressurized condition to an electrode opposite the cathode electrode.