A composition that includes a dispersion stabilizer for an electrode coating liquid for a power storage device is provided. The composition has superior ability to stably disperse an electrode active material and a conductive material, and makes it possible to manufacture a uniform electrode, even when a dispersion device that has weak shear force is used. A dispersant for an electrode coating liquid for a power storage device, the dispersant being characterized by containing cellulose fibers that satisfy (a)-(c). (a) The number average width of the short widths is 2-200 nm. (b) The aspect ratio is 7.5-250. (c) Cellulose I crystals are included and the crystallinity thereof is 70%-95%.