A magnetic storage element includes a magnetic nanowire. A cross-section of the magnetic nanowire has first and second visible outlines, the first visible outline has a first minimal point at which a distance from a virtual straight line becomes minimal, a second minimal point at which the distance from the virtual straight line becomes minimal, and a first maximal point at which the distance from the virtual straight line becomes longest between the first minimal point and the second minimal point, and an angle between a first straight line connecting the first minimal point and the second minimal point, and one of a second straight line connecting the first minimal point and the first maximal point and a third straight line connecting the second minimal point and the first maximal point is not smaller than four degrees and not larger than 30 degrees.