To provide a motor rotation data detecting method and a motor rotation data detecting device capable of detecting rotation data accurately without causing a braking time to become longer when stopping a motor, even if rotational speed is slow when the motor starts rotating or immediately before it stops and so on.

A rotation signal generator 6 generates a pulse signal of a ripple component from a waveform of a motor current 'i' detected by a current detector 4. Based on the pulse signal, a rotational amount estimator 8 estimates the rotational amount of the motor M. Also, a counter electromotive voltage Vg is estimated by a counter electromotive voltage estimator 5 from a voltage Vm between motor terminals detected by an inter-motor-terminal voltage detector 3 and the motor current 'i' detected by the current detector 4. Then, a counter electromotive integration calculator 7 performs integration every pulse period of the pulses for the counter electromotive voltage Vg. Based on the result of this integration, correction is made for the rotational amount of the motor M estimated by the rotational amount estimator 8 at a rotational amount determiner and corrector 9.

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