A magnetic sensor includes a bridge circuit with a first, a second, a third, and a fourth resistor annularly and electrically connected together in this order, and a compensation resistor. The compensation resistor is connected to a first point between the fourth resistor and the first resistor. The first to fourth resistors include a first to fourth tunnel magneto-resistance element, respectively. Each of the magnetization directions in the magnetization fixed layers in the second and fourth magneto resistance elements is opposite to the magnetization direction in the magnetization fixed layer in the first magneto resistance element. The magnetization direction in the magnetization fixed layer in the third magneto resistance element is the same as the magnetization direction in the magnetization fixed layer in the first magneto resistance element. The resistance of the compensation resistor varies with a period of 180 degrees with respect to a rotation angle of the external field.