In a magnetic rotation angle sensor for detecting a rotation angle of a detection target, a yoke covers outer circumferences of a magnet and a Hall device. One of the magnet and the magnetic flux density detection device rotates together with the detection target. The Hall IC is radially shifted from a rotation center of the detection target. The magnetic flux density detection device has a detection surface that is in parallel to one of a tangential direction and a normal direction of a turning circle. The magnet is magnetized in the one of the tangential direction and the normal direction of the turning circle.