A GSR sensor element, which is a super-high-sensitivity micro magnetic sensor based on the GHz spin rotation effect, comprising: an electrode wiring board; a magnetic wire that is a magnetosensitive body formed on the electrode wiring board and includes a pair of magnetic wires (21, 22) being arranged so that the current directions thereof are opposite from each other through an insulating material, wherein one of the pair of magnetic wires is arranged parallel with the other one of the pair of magnetic wires; a coil including a coil lower part, a coil upper part, and a joint part connecting both (31, 32), wherein the coil lower part is formed on the electrode wiring board, the coil upper part is formed from an upper part of a pair of magnetic wires (21, 22) to the side through an insulating material and then onto the electrode wiring board, and the end part of the coil lower part and the end part of the coil upper part form the joint part on the electrode wiring board to be connected to each other; and four terminals (23, 25, 34, 36) formed on the surface of the electrode wiring board for connection to an external integrated circuit, two of the four terminals (34, 36) coupled with end parts of the coil and the other two of the four terminals (23, 25) coupled with the pair of magnetic wires (21, 22) for connection to an external integrated circuit, wherein other ends of the pair of magnetic wires (21, 22), which are not coupled with the other two of the four terminals (23, 25), are connected through a wire joint part (21B, 22B) and a wire connection portion, characterised in that the coil is multiply wound around the pair of magnetic wires (21, 22), and the pair of magnetic wires (21, 22) are separated by an insulating wall insulating the pair of magnetic wires (21, 22) from each other in the coil. an electrode wiring board; a magnetic wire that is a magnetosensitive body formed on the electrode wiring board and includes a pair of magnetic wires (21, 22) being arranged so that the current directions thereof are opposite from each other through an insulating material, wherein one of the pair of magnetic wires is arranged parallel with the other one of the pair of magnetic wires; a coil including a coil lower part, a coil upper part, and a joint part connecting both (31, 32), wherein the coil lower part is formed on the electrode wiring board, the coil upper part is formed from an upper part of a pair of magnetic wires (21, 22) to the side through an insulating material and then onto the electrode wiring board, and the end part of the coil lower part and the end part of the coil upper part form the joint part on the electrode wiring board to be connected to each other; and four terminals (23, 25, 34, 36) formed on the surface of the electrode wiring board for connection to an external integrated circuit, two of the four terminals (34, 36) coupled with end parts of the coil and the other two of the four terminals (23, 25) coupled with the pair of magnetic wires (21, 22) for connection to an external integrated circuit, wherein other ends of the pair of magnetic wires (21, 22), which are not coupled with the other two of the four terminals (23, 25), are connected through a wire joint part (21B, 22B) and a wire connection portion, characterised in that the coil is multiply wound around the pair of magnetic wires (21, 22), and the pair of magnetic wires (21, 22) are separated by an insulating wall insulating the pair of magnetic wires (21, 22) from each other in the coil.