A magnetic element capable of generating one skyrmion and erasing the one skyrmion, comprising: a thin film magnet having substantially rectangular flat plate-like shape, an upstream electrode connected to the thin film magnet in a width Wm direction of the thin film magnet and made of a non-magnetic metal; a downstream electrode connected to the thin film magnet in the width Wm direction to oppose the upstream electrode and made of a non-magnetic metal; a skyrmion sensor configured to detect the skyrmion, a width Wm of the substantially rectangular thin film magnet being such that 3·λ > Wm ≥ λ, λ denoting a diameter of the skyrmion, a length Hm of the substantially rectangular thin film magnet being such that 2·λ > Hm ≥ λ, the thin film magnet having a notch structure at an edge between the upstream electrode and the downstream electrode, a first corner of the notch structure opposing the upstream electrode having an interior angle of 180 degrees or larger, the interior angle denoting an angle of a corner formed in the thin film magnet, the first corner being positioned closer to the downstream electrode with respect to a center of the thin film magnet in the width Wm, magnet and the upstream electrode being such that 2·λ > S1 ≥ 0.52·λ, λ denoting a diameter of the skyrmion to be generated in the thin film magnet, a width w of the notch structure of the thin film magnet being such that 0.5·λ > w > 0.2·λ, λ denoting a diameter of the skyrmion to be generated in the thin film magnet, a length h of a side of the notch structure of the thin film magnet opposing the upstream electrode being such that 0.8·λ ≥ h ≥ 0.2·λ, λ denoting a diameter of the skyrmion to be generated in the thin film magnet, a distance S2 between a second corner of the notch structure of the thin film magnet opposing the first corner and the downstream electrode being such that 0.5·λ ≥ S2, λ denoting a diameter of the skyrmion to be generated in the thin film magnet, the thin film magnet at least exhibiting a skyrmion crystal phase in which the skyrmion develops and a ferromagnetic phase according to a magnetic field applied thereto, and the skyrmion being generated by a pulse current applied to the thin film magnet to flow in a direction from the upstream electrode to the downstream electrode. a thin film magnet having substantially rectangular flat plate-like shape, an upstream electrode connected to the thin film magnet in a width Wm direction of the thin film magnet and made of a non-magnetic metal; a downstream electrode connected to the thin film magnet in the width Wm direction to oppose the upstream electrode and made of a non-magnetic metal; a skyrmion sensor configured to detect the skyrmion, a width Wm of the substantially rectangular thin film magnet being such that 3·λ > Wm ≥ λ, λ denoting a diameter of the skyrmion, a length Hm of the substantially rectangular thin film magnet being such that 2·λ > Hm ≥ λ, the thin film magnet having a notch structure at an edge between the upstream electrode and the downstream electrode, a first corner of the notch structure opposing the upstream electrode having an interior angle of 180 degrees or larger, the interior angle denoting an angle of a corner formed in the thin film magnet, the first corner being positioned closer to the downstream electrode with respect to a center of the thin film magnet in the width Wm, magnet and the upstream electrode being such that 2·λ > S1 ≥ 0.52·λ, λ denoting a diameter of the skyrmion to be generated in the thin film magnet, a width w of the notch structure of the thin film magnet being such that 0.5·λ > w > 0.2·λ, λ denoting a diameter of the skyrmion to be generated in the thin film magnet, a length h of a side of the notch structure of the thin film magnet opposing the upstream electrode being such that 0.8·λ ≥ h ≥ 0.2·λ, λ denoting a diameter of the skyrmion to be generated in the thin film magnet, a distance S2 between a second corner of the notch structure of the thin film magnet opposing the first corner and the downstream electrode being such that 0.5·λ ≥ S2, λ denoting a diameter of the skyrmion to be generated in the thin film magnet, the thin film magnet at least exhibiting a skyrmion crystal phase in which the skyrmion develops and a ferromagnetic phase according to a magnetic field applied thereto, and the skyrmion being generated by a pulse current applied to the thin film magnet to flow in a direction from the upstream electrode to the downstream electrode.