A nonaqueous electrolyte secondary battery includes a positive electrode plate including a positive electrode core and a positive electrode mixture layer formed thereon; a negative electrode plate including a negative electrode core and a negative electrode mixture layer formed thereon; a wound electrode assembly in which the positive electrode plate and the negative electrode plate are wound with a separator therebetween so as to be insulated from each other; a nonaqueous electrolyte solution; a pressure-responsive current interruption mechanism electrically connected to at least one of the positive electrode plate and the negative electrode plate; and an outer casing. Excess electrolyte solution is present outside the electrode assembly in the outer casing. The liquid level of the excess electrolyte solution is at such a height that the excess electrolyte solution does not come into contact with a component of the current interruption mechanism when the outer casing is placed horizontally.