To provide a technique for reducing measurement errors in a rotation angle caused by an axial shift of a magnet in a rotation sensor including a magnet part rotated in conjunction with a rotator to be measured and a magnetic sensor separated from the magnet part by a prescribed interval and detecting the rotation angle of the rotator to be measured on the basis of an output from the magnetic sensor.

The magnet part 11 of the rotation sensor 1 includes: a disk-like magnet body 111 arranged so that one major surface is disposed opposite a substrate 13 to which the magnetic sensor is attached; and a resin-made magnet holder 112 intervening between the magnet body 111 and the substrate 13 and brought into slide contact with the substrate 13.