A method for producing an electrode film for an electric double-layer capacitor, the method comprising: a step of kneading a carbonaceous powder, a conductive assistant, and a fluororesin binder, and producing a shaped product from the obtained kneaded product; a step of pulverizing the shaped product to produce a modifying material having an average particle diameter of 5 to 100 μm; and a step (b) of kneading a carbonaceous powder, a conductive assistant, a fluororesin, and the modifying material, said modifying material being present in a ratio of 1 to 40% by weight with respect to 100% by weight in total of the carbonaceous powder, the conductive assistant, the fluororesin, and the modifying material, and rolling the obtained kneaded product to produce an electrode film for an electric double-layer capacitor, wherein the modifying material has an angle of repose of 45 degrees or less, and said angle of repose is measured by using a method in which a powder collection board having a diameter of 80 mm is placed, and then a funnel having a nozzle with an inner diameter of 7 mm is placed so that the lower end of the nozzle is positioned at a height of 75 mm from the powder collection board, the modifying material is supplied into the funnel while being vibrated using a dispersing sieve, and is gently dropped from the funnel onto the powder collection board, followed by measurement of an angle (an angle of repose) formed by an inclined surface of a conical powder layer formed on the powder collection board and a horizontal surface; and irradiating the shaped product or a pulverized product thereof with an electron beam at step. a step of kneading a carbonaceous powder, a conductive assistant, and a fluororesin binder, and producing a shaped product from the obtained kneaded product; a step of pulverizing the shaped product to produce a modifying material having an average particle diameter of 5 to 100 μm; and a step (b) of kneading a carbonaceous powder, a conductive assistant, a fluororesin, and the modifying material, said modifying material being present in a ratio of 1 to 40% by weight with respect to 100% by weight in total of the carbonaceous powder, the conductive assistant, the fluororesin, and the modifying material, and rolling the obtained kneaded product to produce an electrode film for an electric double-layer capacitor, wherein the modifying material has an angle of repose of 45 degrees or less, and said angle of repose is measured by using a method in which a powder collection board having a diameter of 80 mm is placed, and then a funnel having a nozzle with an inner diameter of 7 mm is placed so that the lower end of the nozzle is positioned at a height of 75 mm from the powder collection board, the modifying material is supplied into the funnel while being vibrated using a dispersing sieve, and is gently dropped from the funnel onto the powder collection board, followed by measurement of an angle (an angle of repose) formed by an inclined surface of a conical powder layer formed on the powder collection board and a horizontal surface; and irradiating the shaped product or a pulverized product thereof with an electron beam at step.