A non-aqueous electrolyte secondary battery includes a housing, a stack-type electrode array accommodated in the housing, and an electrolyte solution. The electrolyte solution includes an infiltrated portion infiltrated into the stack-type electrode array and an excess portion other than the infiltrated portion. In a set-up state that the non-aqueous electrolyte secondary battery is arranged such that a direction of stack of the stack-type electrode array is orthogonal to a vertical direction, a lower end of the separator projects below lower ends of the positive electrode and the negative electrode. In the set-up state, within a range of an operating state of charge, a projecting portion of any of the plurality separators is always in contact with the excess portion and the plurality of positive electrodes and the plurality of negative electrodes are not in contact with the excess portion at any time.