ROTATION ANGLE DETECTION DEVICE

Provided is a rotation angle detection device capable of obtaining a detection result in a wider angle range with high accuracy. A rotation angle detection device 1 is provided with a part to be detected 4 which is attached to a throttle shaft S by a rotor 3, and a Hall IC 5 which detects magnetic flux components of the part to be detected 4. The Hall IC 5 is provided with a magnetism collecting plate 51 which is disposed facing the part to be detected 4 and extends along the rotation surface of the part to be detected 4, and Hall elements 52 which detect the magnetic flux components of the part to be detected 4, and output a signal corresponding to the rotation position of the throttle shaft S on the basis of the results of the detection by the Hall elements 52. The Hall elements 52a, 52c each detect a magnetic flux component in an X-axis direction passing through the rotation axis of the throttle shaft S. The Hall elements 52b, 52d each detect a magnetic flux component in the Y-axis direction passing through the rotation axis of the throttle shaft S. The part to be detected 4 is configured by combining a semicircular yoke 41 with a semiannular magnet 42.