An electric storage device having a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The positive electrode has a positive substrate layer, a positive composite layer containing a positive active material, and an undercoat layer located between the positive substrate layer and the positive composite layer. A density of the positive composite layer is 2.1 g/cm3 or more and 2.7 g/cm3 or less. The positive electrode has the rate of increase in sheet resistance after a solvent immersion test of 30% or less. The undercoat layer contains a binder selected from the group consisting of chitosan derivatives, cellulose derivatives and acrylic acid derivatives.