PROBLEM TO BE SOLVED: To provide an angle sensor capable of being easily incorporated into a ball joint and measuring the rotating angles of the ball joint on three axes.
SOLUTION: Two first coils 22a, 22b with their centers coinciding with the center of the sphere portion 12 of a ball joint are wound on the outer surface of the sphere portion 12, and the sphere portion is freely rotatably and slidably mounted within an approximately spherical recess formed in a receiving member 14. A joint shaft 10 extends from the spherical portion. Two second coils 24a, 24b surrounding the recess and having their centers coinciding with the center of the sphere portion are wound on the receiving member. Voltages of different frequencies are supplied to the second coils to generate alternating magnetic fields, and electromotive forces induced on the first coils by the alternating magnetic fields are separated from one another according to frequency and detected. The rotating angles of the joint shaft about three axes are calculated from the induced electromotive forces detected.