PURPOSE: To provide a highly reliable magnetic angle sensor equipped with a main circuit, and a spare circuit.

CONSTITUTION: The sensor is provided with a first, a second, a third and a fourth magnetoresistance effect elements 10, 11, 12 and 13 formed of a magnetoresistance effect material zigzag on a plane. The first and second magnetoresistance effect elements are connected in series thereby to constitute a first series-connected circuit, while the third and fourth magnetoresistance effect elements are connected in series to constitute a second series-connected circuit. The first and second series-connected circuits are arranged to face each other. The magnetic angle sensor with rotary magnetic fields 21 and 22 orthogonal to surfaces of the magnetoresistance effect elements uses the first series-connected circuit as a main circuit, and the second series-connected circuit as a spare circuit.