To prevent the coming-off of a magnetoresistance element and to improve safety by soldering the connecting terminal of the magneto-resistance element as a rotation detecting element to the lower surface side of a circuit board for detecting rotation and providing a coming-off preventing member for the magnetoresistance element.

A circuit-consisting element to constitute a circuit for creating rotation angle information with the rotation of a steering wheel and magnetoresistance elements 57 and 58 as rotation detecting elements for detecting the rotation of driven gears 39 and 40 are mounted to the lower surface side of a circuit board 41, and the connecting terminal 57a of the magentoresistance element 57 is soldered to the circuit board 41. In addition, a coming-off preventing member 80 to prevent the coming-off of the magnetoresistance element 57 mechanically is provided. The coming-off preventing member 80 comprises a pair of fitting claws 80a, and the top parts of the fitting claws 80a are slotted. The coming-off preventing member 80 is fixed to the circuit board 41 by fitting the fitting claws 80a into the fitting holes 41a of the circuit board 41.