Abstract: The present invention is mainly configured of a separator for an electric double-layer capacitor that comprises an aramid fiber, a polyester fiber, a glass fiber, and a silica (inorganic compound for forming hydrosol) containing a particulate silica (particulate inorganic compound) of not less than 1 nm and not more than 500 nm, wherein total of the silica and the glass fiber is not less than 10 mass percent and not more than 50 mass percent; the electric double-layer capacitor comprising the separator; and a manufacturing method of the separator for the electric double-layer capacitor which method comprises a mixing process for mixing the aramid fiber, the polyester fiber, the glass fiber, and the silica sol and a paper making process for making paper from the mixture.