A binder composition for an electrode of an electric storage device is provided. The binder composition comprises (A) at least one polymer selected from the group consisting of polyamic acids and imidized polymers thereof having an imidization rate of 50% or less and (B) water. The ratio Ma/Mb of the content of the polymer (A), Ma (parts by mass), to the content of the water (B), Mb (parts by mass), ranges from 500 to 5,000. The binder composition for an electrode of the present invention provides an electric storage device having a large charge/discharge capacity and a low degree of capacity degradation due to repetition of a charge/discharge cycle.