A non-volatile storage element 100 has a silicon substrate 102, a first memory region 106a composed of a first lower silicon oxide film 108a, a first silicon nitride film 110a, and a first upper layer silicon oxide film 112a provided in this order, a second memory region 106b composed of a second lower layer silicon oxide film 108b, a second silicon nitride film 110b, and a second upper layer silicon oxide film 112b provided in this order, and a first control gate 114 and a second control gate 116 arranged on the first memory region 106a and the second control gate 116, respectively, on the silicon substrate 102. The silicon nitride film 110 is provided so as to be horizontal in a direction within a substrate plane.