A method for adjusting an encoder directly coupled with a brushless motor, wherein a set of sensor match marks are provided on a sensor base plate mounting a number of sensor elements, while another set of disc match marks are provided on an encoder disc at positions where, during the time when the motor is energized but locked, a phase difference between an EMF voltage waveform of the motor and the output voltage waveform of a specific phase of the encoder is made equal to a predetermined value, rough adjustment of the encoder is executed by aligning the two sets of match marks between each other, a gap between the encoder disc and the sensor is adjusted suitably, and then the sensor base plate is slightly rotated relative to the stator of the brushless motor for executing a fine adjustment of the encoder.