PURPOSE:To enhance detection accuracy and expand angle detection range by causing two pairs of magnetic sensors to provide outputs of sine wave signals with phase difference of 1/4 wavelength for a rotating field of permanent magnet and by executing linear signal processings through operations for each 1/4 wavelength. CONSTITUTION:At the one end of an operation lever 1, a non-magnetic ball 2 is fixed, and a cylindrical permanent magnet 3 which is magnetized in the axial direction is buried within the ball 2. The lever 1 and magnet 3 commonly have the same center line passing the center of ball 2, and the ball 2 is supported in precession free by the ball support 4. The magnetic sensors 10, 11 are buried in the ball support 4 and arranged at right angles each other. The sensors 10, 11 are configurated by an MR element and output the sine waves containing phase difference of 1/4 wavelength for the rotating field of magnet 3. Outputs V1, V2 and V3, V4 are given to the operation circuits 12, 13 and these are operated for each 1/4 wavelength and are linearized. Thereby, an output linearized for magnetic field angle can be obtained corresponding to rotating angle and inclination angle of the lever 1. Thus, detection accuracy can be improved and angle detection range can also be widened.