To provide a motor rotation information detecting apparatus having control consistency and reliably detecting motor rotation information even if a filter is used and has a changeable pass frequency band.

A switched capacitor filter (SCF) 7 is used and extracts a ripple component from a motor current i detected by a motor current detecting section 4. The ripple component in the current is converted into a pulse signal by a binarization process of a comparator 8. A counter electromotive voltage estimating section 5 estimates a counter electromotive voltage Vg based on a voltage Vm across terminals of a motor M detected by a section 3 for detecting the voltage across the terminals of the motor and the motor current i detected by the motor current detecting section 4. The pass frequency band of the switched capacitor filter 7 is variably controlled in response to a rotation speed of the motor M based on the counter electromotive voltage Vg by utilizing a proportional relationship between the counter electromotive voltage Vg and the rotation speed of the motor M.