A magnetic storage device includes a magnetic yoke. A maximum thickness of each open end of the magnetic yoke in a diameter direction of the magnetic yoke is set to be larger than a maximum thickness of a second magnetic layer of a magnetoresistive element in the diameter direction of the magnetic yoke, thereby materializing the shape of the magnetic yoke. Moreover, a magnetic field generated from the magnetic yoke can be increased by optimization of the shape of the magnetic yoke, thereby reducing writing current.