The present invention provides a non-aqueous electrolyte secondary battery including: a positive electrode including a first active material capable of occluding and releasing a lithium ion and a second active material capable of occluding and releasing an anion; a negative electrode including a negative electrode active material capable of occluding and releasing a lithium ion; and an electrolyte containing a salt of a lithium ion and the anion. The second active material is a polymer having a tetrachalcogenofulvalene skeleton in a repeating unit. According to the present invention, provided is a non-aqueous electrolyte secondary battery with improved output characteristics, in particular, a pulse discharge characteristic, without a significant decrease in energy density.