An MI sensor includes: an amorphous wire; an insulator layer formed on an outer peripheral surface of the amorphous wire; and an X-axis coil, a Y-axis coil, and a Z-axis coil which are formed, in a spiral shape, on an outer peripheral surface of the insulator layer. The X-axis coil, the Y-axis coil, and the Z-axis coil are formed of a conductive layer, and the X-axis coil, the Y-axis coil, and the Z-axis coil are arranged in directions orthogonal to each other.