There are provided a battery electrode wherein an active material layer is formed on a collector surface, and the layer contains an active material and a block copolymer having a vinyl alcohol polymer block; and a lithium ion secondary battery having a laminate structure in which a pair of electrodes having an active material layer are disposed in such a manner that the active material layers face each other via a separator, and an electrolyte composition containing a lithium-containing electrolyte salt fills the gaps between the pair of electrodes and the separator, wherein at least one of the pair of electrodes is the above battery electrode. Thus, there can be provided a lithium ion secondary battery which can be easily produced and be less polarized, exhibiting excellent charge/discharge properties and cycle characteristics.