The present invention provides for a nonaqueous electrolyte secondary battery and a producing method therefor, in which a grooved portion provided in an upper portion of the outer casing of the nonaqueous electrolyte secondary battery protrudes toward the inner portion of the outer casing, a group of electrodes being housed in the outer casing, a positive electrode and a negative electrode being wound in a spiral manner while facing each other through a separator in the group of electrodes, and a sealing member is placed on the upper portion of the grooved portion through insulated packing to seal the opening of the outer casing in an airtight manner, and whereby a circular insulating plate 10 provided with an arced opening 12 and cut portions 13 and 14 is arranged between the upper portion of the group of electrodes and the lower surface of the grooved portion, the cut portions 13 and 14 extending from end portions 12a and 12b of the opening 12, and the inner peripheral side of the cut portions 13 and 14 of the circular insulating plate is raised from the outer peripheral side of the cut portions 13 and 14. Such insulating plate does not adversely affect the injection property of the electrolytic solution used in producing the nonaqueous electrolyte secondary battery as to provide it with excellent battery performance and excellent productivity.