PURPOSE: To simplify construction and to reduce errors in detection by providing magnetic poles projecting respectively inward in a diametral direction on the quadrisections of a circumference and providing a stator, etc. applied with primary windings and secondary windings respectively on these magnetic poles.

CONSTITUTION: A detector for rotating angle is mainly constituted of a stator 10 having magnetic poles 11, 12, 13, 14 projecting respectively inward in a diametral direction on the quadrisections of a circumference and applied with primary windings 11a, 12a, 13a, 14a and secondary windings 11b, 12b, 13b, 14b on these magnetic poles, and a rotor 20 having the shape wherein a circular column is cut to a V shape from the side thereof, and held freely turnably with a shaft 21 while the circular cylindrical surface thereof is held oppositely to the projecting end faces of the magnetic poles 11, 12, 13, 14. The constitution is thus simplified, and an error known as a slot ripple is eliminated, whereby the accuracy in detection is improved.