A power storage device electrode is provided, which includes a layer made of a composite material containing an organic sulfide compound (A) as an electrode active material and a sulfide-containing organic polymer (B) as a binder, and a current collector stacked on the layer. The power storage device electrode is used as a positive electrode of a power storage device. Therefore, the power storage device is less liable to suffer from reduction in capacity during repeated charge/discharge, and has a higher capacity density and a higher energy density.