To provide a drive unit for brushless motor which can suppress rotation irregularity.

This drive unit for brushless motor, which detects the rotational position of the rotor of a brushless motor and switches the current application to two or more phases of stator coils separately for each phase, is equipped with a step cycle measuring means 8 which measures the step cycle where the rotor rotates to one time of current application to each phase, based on the detected interval of the rotational position of the rotor, a rotation cycle measuring means 6 which measures the rotation cycle where the rotor rotates at least once, synchronizing with the detection timing of the rotational position of the rotor, a reference step cycle computing means 7 which computes the reference step cycle, based on the rotation cycle, an error detection means 9 which gets an error by the cycle difference between the step cycle and the reference step cycle, and a correction means 10 which corrects the current application method in the next switching of current application to the stator motor, based on the error.

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