Rotational angle detecting device

A rotational angle detecting device for detecting a rotational angle of a rotating object, comprising:

• a magnetic member generating a magnetic field;
• a magnetic sensor including a first sensor element and a second sensor element that are disposed to rotate relative to the magnetic member in accordance with a rotation of the rotating object, and respectively output first signals and second signals according to a change in the magnetic field caused as rotating relative to the magnetic member;
• and
• a processing unit capable of processing first output values of the first sensor element and second output values of the second sensor element, the processing unit including:
• means for acquiring the first output value and the second output value at every angle of rotation of the rotating object;
• means for generating a first estimation waveform and a second estimation waveform from the first output values and the second output values acquired by the means for acquiring the first output value and the second output value, the first estimation waveform corresponding to a waveform for one cycle of the first signals, and the second estimation waveform corresponding to a waveform for one cycle of the second signals;
• means for adjusting an amplitude of the first estimation waveform and an amplitude of the second estimation waveform to be equal;
• and
• means for calculating a rotational angle of the rotating object by a trigonometric function operation based on the first output value, the second output value, and an adjusted amplitude of the first estimation waveform and the second estimation waveform.