A resolver device (14) includes: a microcomputer (1) for outputting a control signal for driving a motor (4) to a drive circuit (3); a sensor section (5) (resolver) for outputting detection values (a sine signal and a cosine signal) in accordance with a rotation angle of the motor (4); and a signal circuit (13) provided between the microcomputer (1) and the sensor section (5). The microcomputer (1) determines an abnormality when the detection values of the sensor section (5) are out of a first normal range and then determines return of the sensor section (5) to normal when the detection value is present within a second normal range and in a plurality of regions obtained by dividing the first normal range.